Oil Metering Pump

[benspeed]

OK - I have a used OMP that I plan to install to hopefully remediate the "limp mode" situation I've been dealing with. (Thanks again to Chris for the master switch On/off technique when the car does go into limp mode. Happened again at LRP and I still finished 2nd after doing the reset.)

So, I've got an '89 second gen with the electrical OMP. How do I go about changing this thing over? Seems to be simple, but I always amaze myself by how I can get it wrong. Any special calibration or setup after it's installed? Pointers would be most appreciated.

Thanks,



------------------
BenSpeed
#33 ITS RX7
BigSpeed Racing
NNJR BoD - Treasurer
[email protected]
NNJR

[tims90rx7]

As a competitor of Ben's I actually appreciate it when his car goes into limp mode ;-)

Congrats on the second at LRP...you are turning up the heat in the NAARC standings!

I've gotta get back in my car...see you at NHIS in July?

Tim

------------------
Tim Estes
ITS 1990 RX-7
NER

[Doug Ford]

Hey Ben, it looks like I am having the same problem you are having. I thought that the speedsource cars were disconnected anyway. I have always pre-mixed my gas anyway. I guess I will follow this for instructions.

------------------
SpeedSource rx-7 ITS #12
2004 Suburban white
2001 supercrew white (tow vehicle)
memphis

[its66]

FYI..Mine is still connected. The last time I talked to David, he said to leave it.

Fortunately, I haven't experienced the limp problem, so i won't be much help on that.

Jim
ITS66

[Newbie]

Hey,

Whats Limp Mode??

I have a '87 speedsource and couln't get it past 6000 rpm last race.

[Mike Guenther]

In limp home mode you can't even get to 3000 RPM and the car is bucking and sputtering and wants to just die. Mike Van Steenburg told me that you can attach a good OMP and tie it to the side of the motor and it will fool the computer to keep the motor running. I don't know how that works because I assume that the OMP is putting out a pulse signal to the computer to indicate rate of flow. It the signal generator goes bad then the computer puts the motor in limp home mode so that you don't burn it up rumming without the oil being injected. If you can fool the computer by attaching an OMP without it being installed and turning, then I would like to know just what the computer is looking for in a signal from the OMP. If it is a pulse like I suspect, then merely hanging a good one off the side of the motor wouldn't send out the pulses if it wasn't turning. If it is a pulse then I don't understand how the trick would work. Also if it is a pulse, it could be simulated easily and a foolproof way to satisfy the computer could be cheaply devised. You would need to pre-mix to preven engine damage in the event that your OMP failed and the computer was fooled by the simulator.

[Newbie]

I assume the electrical signal is only in the S5 motors since my S4 has a mechanical pump.

Whatever the case, the problem I'm having sounds similar to Limp Mode. Unfortunately, for me it means limping around the track, taking 3rd gear turns in 4th.

What the heck is wrong with this motor???

[bldn10]

To eliminate limp mode issues add the following to your fuel:

Sprints - Viagra

Enduros - Levitra

Unsure - Cialis

------------------
Bill Denton
87/89 ITS RX-7
02 Audi TT225QC
95 Tahoe
Memphis

[benspeed]

Hey Tim - I'll definitely see you at NHIS. I'm coming up early to practice, I want to be in the 1:14s http://ITForum.ImprovedTouring.com/smile.gif

Mike Vansteenberg told me about the trick of hanging a good OMP on the side of the motor as a temp trick. Not sure why it works.

I do pre-mix my gas - Rx7 guys should do that for motor insurance. 5 oz of 2 stroke oil to 5 gallons of gas. From what I understand most 13b race motors have the pump disconnected to everything but the computer - but I'm not an expert.

I will call ISC Racing - Mike V - and see if he will give me the download on how to do the replacement. NHIS is a twisty track that has no chance to do the reset trick without danger of missing a turn.

Cheers,

[C. Ludwig]

Originally posted by Mike Guenther:
In limp home mode you can't even get to 3000 RPM and the car is bucking and sputtering and wants to just die. Mike Van Steenburg told me that you can attach a good OMP and tie it to the side of the motor and it will fool the computer to keep the motor running. I don't know how that works because I assume that the OMP is putting out a pulse signal to the computer to indicate rate of flow. It the signal generator goes bad then the computer puts the motor in limp home mode so that you don't burn it up rumming without the oil being injected. If you can fool the computer by attaching an OMP without it being installed and turning, then I would like to know just what the computer is looking for in a signal from the OMP. If it is a pulse like I suspect, then merely hanging a good one off the side of the motor wouldn't send out the pulses if it wasn't turning. If it is a pulse then I don't understand how the trick would work. Also if it is a pulse, it could be simulated easily and a foolproof way to satisfy the computer could be cheaply devised. You would need to pre-mix to preven engine damage in the event that your OMP failed and the computer was fooled by the simulator.


I posted this in another OMP thread but here goes again. The S4 electronics do not monitor the OMP. The OMP function of the S4 is wholey mechanical. There is a stepper motor built into the S5 OMP. It's the round, black case on the side of the OMP. The engine turns the pump but the stepper motor is what meters the oil flow. The ECU controls and monitors the stepper motor. It has no control or feedback over the actual pump that is driven off the engine. So the OMP can be detached from the block and as long as it's in good order and plugged in the stepper motor will continue to function and provide the proper feedback to the ECU.

The stepper runs a plunger that meters the oil flow. There is a variable resistor that rides up and down on the plunger. The resistor is shimmed with thin metal spacers to provide the proper voltage range. The ECU needs to see a variable voltage while the pump is in operation. You cannot fix the voltage in the center of the range with a fixed resistor and avoid limp mode. The voltage needs to fluctuate in accordance with load and RPM. When the ECU sees X load at Y RPM and the position of the plunger doesn't correspond the fun ends.

When the OMP goes bad it's possible for them to take the ECU out with it. Haven't confirmed this but it's well rumored. Changing to a known good OMP won't always cure the problem without also changing to a known good ECU.

When limp mode occurs the secondary injectors are shut down. When that happens the engine goes extrememly lean over the 3800rpm switch over point. Lean enough it won't rev past that point at full load. You can rev the engine with no load and part throttle. But load it and go WOT and it falls flat. It sounds like you've hit a soft rev limiter. Pop, sputter, etc. If the car is revving strongly past 4000rpm but encountering problems higher in the rev range the problem is not limp mode related.

------------------
Chris Ludwig
08 ITS RX7 CenDiv

[This message has been edited by C. Ludwig (edited June 07, 2005).]

[Mike Guenther]

Chris,
you Da Man! Thanks for that info.

[benspeed]

Chris - awesome update - that is some quality technical info. I will also look into getting a new ECU since my car is also breaking up over 7800 rmp. ECU is cheap compared to an OMP. New OMP is like $1000. I bought a used one for $250 and hope that it's good.

[paulydee]

Ben,

The 7800 RPM breakup is actually the rev limiter coming into play. I had this problem consistenty, and very noticeable on dyno pulls. I got the rev limiter remove and now the engine pulls clean all the way to 9K.

------------------
Paul D'Angelo
73 ITS CENDIV
Indy Region
http://www.iridiumracing.com
http://www.iridiumracing.com/headernew.jpg

[benspeed]

Hi Chris - no rev limiter in the car - she'll pull through 10K. But around 7800-8000 folks at Start Finish tell me it sounds like I'm hitting a rev limiter. Car still pulls and I don't hear or feel any sputter, but when I rev it while parked I can hear minor breakup - it's not real bad, but not good for performance.

Any ideas? Got new plugs in, ground looks good, wires have 2 seasons on them - might replace those. ECU related to the OMP??

[Newbie]

How do you remove the rev limiter from the ECU?

[paulydee]

You have to send it out to get reprogrammed.

[Doug Ford]

My cars runs fine until the cars runs for a while. For example at the last race I ran practice/qualifying on Saturday morning and it seemed to run fine. Although my times were about a 1 seconds off my normal pace (no clean laps due to traffic). In the race I ran about 2-3 laps and it went into what I was calling limp mode. On my car I have a Pi dash and all of a sudden the RPM guage goes away and the car just doesn't run very well at all. It will rev past 3,000 b ut my times drop by about 2-3 seconds a lap and you can feel in in the lost horse power. I remembered this thread and I turned the kill switch off and back on and the car satrted running again like normal then after about a half a lap it happen again. I am not sure whether this is the limp mode thing but with some of the description I have read it sounds like some of them but not all of them. Any help would be appreciated. I plan on trying a different OMP and maybe an alternate computer just to see if it fixes it. I would just like to know what everyone else thinks and if the OMP change fixes the problem.



------------------
SpeedSource rx-7 ITS #12
2004 Suburban white
2001 supercrew white (tow vehicle)
memphis

[seckerich]

Check your trailing coil and the grounds to it. The tach signal is all from that coil and they will drop out if they are searching for a ground or the coil is bad.
Steve Eckerich
ITS Speedsource RX7

[benspeed]

Doug - what you describe sounds like trouble I've had. Here's the rundown on stuff to check:

Throttle position sensor screwing up your computer
OMP screwing up the computer
Mass airflow sensor wires busted/chafing and screwing up your computer
Ground loose
ECU going bad
OR - secondary injectors clogging. This last one took forever to figure out since we have to take the air/fuel system apart to find the problem

I'm betting OMP because you are going into safety mode or limp mode. Can you letup on the gas and she wants to come to life, then you floor it and she dies again?

Let us know what you find.

Cheers,

Ben

PS - still trying to find time to change my OMP - I'll let you know what happens after the race on 7/9 at NHIS.

[bldn10]

Doug and I were talking about his problem and he had been thinking OMP. I was reading my Haynes manual on it and it sounded like you either have an electronic or mechanical unit. I see from Chris' post that indeed the S4 cars have a mechanical pump and the S5 an electronic one. Therefore, doesn't that mean that a limp mode problem in an S4 car cannot be the OMP? Since there is no signal to or from the ECU, the ECU can't be directly affected. (Which is not to say that a fauly OMP might not ultimately have an effect on how the engine runs.) The weird thing is that Doug's what-we-thought-to-be all-S5 car has a mechanical pump.

Steve, we made the tach-trailing coil connection and tried 3 different coils w/o success. We also tried a different fuel rail and crank angle sensor. Doug had lost the screw on the TPS and we eyeballed it - can it be off so bad as to cause this?

Let me throw this out for consideration -water thermosensor. If it is erroneously telling the ECU that the engine is burning up, could that not cause the ECU to go into limp?

Anyone other than Paul going to Mid-Ohio next weekend?

------------------
Bill Denton
87/89 ITS RX-7
02 Audi TT225QC
95 Tahoe
Memphis

[benspeed]

Hey Bill - there's a guy here in the NE who I understand had a mechanical pump on the S5 motor. He'd run OK for 3 laps and then crap out. Took him forever to figure out he needed the electrical pump.

I'm no expert - but this guy had the worst luck at the track until he got this sorted out. I'm pretty sure his name is Mark Lovell. Mark, if your out there let us know what you learned.

Cheers,

bp

[C. Ludwig]

I'll be at Mid-Ohio. Will try to paddock near Paul by the Truechoice building.

------------------
Chris Ludwig
08 ITS RX7 CenDiv

[This message has been edited by C. Ludwig (edited June 21, 2005).]

[Eagle7]

I'm tentatively going to be there.

------------------
Marty Doane
ITS RX-7 #13
CenDiv WMR

[bldn10]

Doug and I will be arriving late Fri. - save us some space if possible.

Ben, that sounds like the problem except for one thing - Doug's car has had the same mechanical OMP on it since he got it and this limp mode issue is new. :-/



------------------
Bill Denton
87/89 ITS RX-7
02 Audi TT225QC
95 Tahoe
Memphis

[benspeed]

That's weird - got me stumped.

Y'all gotta give me a race recap - I want to hear the Bill and Doug team were on the podium!

[C. Ludwig]

Originally posted by bldn10:
Doug and I will be arriving late Fri. - save us some space if possible.

Ben, that sounds like the problem except for one thing - Doug's car has had the same mechanical OMP on it since he got it and this limp mode issue is new. :-/




I think in a previous post you said you thought it had all the S5 stuff?

If it's using the S5 computer, harness, sensors, etc and there is no S5 OMP plugged into the harness that is his problem.



------------------
Chris Ludwig
08 ITS RX7 CenDiv

[Doug Ford]

Here is the funny thing. When I bought the car from Jason Sessions in Florida I ran it at Hallet OK, with no problems, the following week we went to Barber AL, and had no problems. Didn't run it until Memphis in March and it was running fine on practice day and in the race on saturday until the tranny let go. I didn't touch the car other than I let Bill Borrow my fuel rail (he was thinking that his was screwing up since his pressure was low) and I pu the rail and injectors back together and put the tranny back in and headed to the track for the May race in Memphis. Well on practice day last two sessions the problem came up. I rememberred the thread on this and turned the kill switch off and it started working again until about 1/2 a lap and started again. The funny thing is that the car will still rev but is just down on power about 2-3 seconds a lap. I come in to the pits and turn the car off and back on and it is fixed until about a 1/2 a lap again. I got the throttle positioning thing back together right based on the two light thing anyway. On Sunday I went out for practice and it ran the whole time without happening but no good laps so I qualified 4 or 5 on the grid with a slow qualifying lap time and when I went out it ran for about a lap or two and I was going to pass a few guys and then it happened again. The wierd thing is my tach on a pie dash will go dead when it happens. The reading just goes completely away and turn the kill switch back on and tach come back up and the motor pulls again and then it goes again. Wierd deal. I have a had the same OMP on the car the whole time. There is on thing that is very obvious, there is not any oil in the lines coming from the OMP they are a clean as a fish tank line, by visual it looks like it is nothing or water running through it. I think I am going to try the OMP and computer and see if I can get it to happen again before going to Mid-Ohio. I would hate to tow that far tand the thing not run worth a shiznit. I am going to get my but kicked anyway so I need to have every edge I can get. Hope to see everyone there.



------------------
SpeedSource rx-7 ITS #12
2004 Suburban white
2001 supercrew white (tow vehicle)
memphis

[benspeed]

Well, the new OMP is now installed (used actually). Racing at NHIS in about 10 days so we'll see how it goes. It gave me one check engine light after I first ran it. Shut it down and the light hasn't come back and I'm hoping the computer was just getting used to a new unit.....

Also traced my ground wire to see if that might be why the car is breaking up a little. The friggin thing was frayed down to mucho bare wire down and contacting the side of the fender! Hopefully that is an easy fix. Couldn't see as it was contacting the car and only after being tugged on did I see the fraying.

[Doug Ford]

Well it appears that it was the computer. I put in a new computer and the problem went away.


------------------
SpeedSource rx-7 ITS #12
2004 Suburban white
2001 supercrew white (tow vehicle)
memphis

[benspeed]

My woes persist badly. Just spent three days at NHIS and never ran a hot lap. Check this out. We replaced:

Computer, 2 oil metering pumps, both coils, crank angle sensor, entire wiring harness, pressure sensor, mass air flow meter, TPS, plug wires, ground wires, added wires, ohmed everything including the injectors. We might try replacing those.

Car will fire up, gets to temperature, hold the throttle at 7000 and it goes right into safety or limp mode. We also cannot get accurate codes from the car. I liked one suggestion which was cut off the front of the car and replace the whole thing!

Suggestions anybody? We had an entire garage of people looking this over - much thanks to everybody, especially Jamie who helped replace the wiring harness.



------------------
BenSpeed
#33 ITS RX7
BigSpeed Racing
NNJR BoD - Treasurer
[email protected]
NNJR

[C. Ludwig]

Well, the CAS was the only thing you didn't mention. Try another one of those.

------------------
Chris Ludwig
08 ITS RX7 CenDiv

[paulydee]

Actually he did mention the CAS or crank angle sensor http://ITForum.ImprovedTouring.com/smile.gif Ben, it sounds like you have a gremlin on a grand scale. Sorry I don't have any thing valuable to offer.

[C. Ludwig]

Oops. Sure did.

[bldn10]

I threw it out once and I might as well do it again since you have tried everything else - water thermosensor. Also, if your car has a resistor in the water thermosensor wire, it might be bad or the wire shorted.

------------------
Bill Denton
87/89 ITS RX-7
02 Audi TT225QC
95 Tahoe
Memphis

[jcmotorsports]

ben
i have a suggestion. BUY A SHOWROOM STOCK CAR!!!!! i am having fun again racing at a national level. and learning to drive MUCH faster.
john costello

[benspeed]

Originally posted by jcmotorsports:
ben
i have a suggestion. BUY A SHOWROOM STOCK CAR!!!!! i am having fun again racing at a national level. and learning to drive MUCH faster.
john costello

I'd go T1 or T2 - something newer that doesn't break or go BMW and have more people in my area who can work on the car. The closest shop for a RX7 is 100 miles.

My hopes are with Flatout Motorsports - looking to see if they fix it and test the car on 8/2 before the LRP race. Eric King is going also.

This much of a pain takes the fun out of racing.

[MaxEnergy]

Bill Denton, re the thermosensor are you refering to the one at the back of the water pump housing that connects to the harness via the green "injector-like" connector? While we were working on Ben's car this weekend someone mentioned that that may be bad a confusing the computer but we didn't have one.

Jamie

------------------
Jamie Kekeisen
86 ITS RX-7 NER
92 325IS under construction

[bldn10]

Yes, that's it; I think it has a green connector. Ben seems to have gone through everything that sends a signal to the ECU except it so it seems the next logical choice. This sensor most assuredly has an effect on how the car runs becuase, as I implied, some people put a variable resistor in the wire that allows some A/F mixture adjustment. It is this sensor that tells the ECU how hot the engine is running - if it says it is too hot, the ECU calls (I think this is right) for more fuel because the relatively cool fuel acts as a coolant, and we all know that a richer mixture runs cooler. If a bogus signal or no signal is received by the ECU, I am speculating that it may go into limp or some mode that mimics limp. If someone spliced a resistor somewhere in the line (to trick the ECU into thinking the engine is running hotter/cooler than it is) either the resistor could be bad or the splice failed. Just grabbing at straws, guys.

------------------
Bill Denton
87/89 ITS RX-7
02 Audi TT225QC
95 Tahoe
Memphis

[benspeed]

Hey Bill - thanks for the suggestion. I'll mention it to Flatout and they can test it. If that's it, I'm buying you mucho beer!

[Andy Bettencourt]

Originally posted by benspeed:
Hey Bill - thanks for the suggestion. I'll mention it to Flatout and they can test it. If that's it, I'm buying you mucho beer!

Fixed...I'll let Ben post the info once he is fully up to speed on the fix...

AB

------------------
Andy Bettencourt
New England Region, R188967
www.flatout-motorsports.com (http://www.flatout-motorsports.com)
http://www.flatout-motorsports.com/images/misc/RX-7_Avitar.jpg

[benspeed]

Well folks - thanks to the diligence of FlatOut, the car is fixed, pending some additional testing. But it basically sounds repaired since we've been able to recreate the problem in the garage.

While we replaced the coils with other used coils, returning the coils back to the originals seems to have made the repair. Many other things were done to the car so who knows - another fix may be in the mix of things, where the coil swapout created another situation. Only the test at the track will tell, but Nick had the car into third gear (cops after him with his hair on fire). Another round of tests at the track and I'm ready for LRP on 8/5.

[benspeed]

Originally posted by C. Ludwig:

When the OMP goes bad it's possible for them to take the ECU out with it. Haven't confirmed this but it's well rumored. Changing to a known good OMP won't always cure the problem without also changing to a known good ECU.



Another intersting note - before this problem occured - After I had replaced the OMP at home - I was running the car at about 2500 RPM to warm the motor before going out to practice and ZAP! - bright white light comes out of the ECU - fried. It fried on a square component on the circuit board near the wire connections - front left of the box when looking at the plug receptacles. It was a black rectangular thing. No damage to wiring. The circuit board looked like the frazzle occured where the wiring diagram indicated wires leading to - guess what - OMP and injectors. Rusty brain tells me it was 3T, 3U, 3V area on the box.

So back to Chris' point - OMP might take down the ECU.

[benspeed]

I wanted to provide a most positive update on the plight of my #33 RX7. After testing the car all day at LRP with Flatout Motorsports, it was clear they did an oustanding job of diagnosing the problem and curing it. A combination of new OMP, dash and engine wiring harnesses and computer did the trick. We suspect that a series of bad OMPs were the cause and that these fried the computer and possible parts of the harness. They dyno tuned to the car and it was making HUGE power.

Not only was the car cured Flatout provided excellent trackside support during the test day. Both myself and Eric King, a quick RX7 shoe, had our cars continuosly improved throughout the day by a sequence of incremental chassis improvements until Eric was able to run a 1:02 flat - his best time by 1.5 seconds! The pricing for this was very reasoanble - I don't think the level of support and knowledge could be matched.

If you want to run quicker times and run up front - give Nick and Adam a call at 978-501-3096.

This is unsolicited from these guys - just my total satisfaction with great service and support.



------------------
BenSpeed
#33 ITS RX7
BigSpeed Racing
NNJR BoD - Treasurer
[email protected]
NNJR

[bldn10]

Uh, I guess you don't want to say how much power - eh?

Like many if not most RX-7 electrical/fuel glitches, yours was solved by changing everything you can think of, and never knowing for sure what it was. Damn these things! But we love em, right?

------------------
Bill Denton
87/89 ITS RX-7
02 Audi TT225QC
95 Tahoe
Memphis

[C. Ludwig]

This is just reason #325 that I feel the ECU rule should be opened up to allow free reign of modification to the electronics and the wiring harness. For $1500 someone can purchase, have installed, and have a baseline tune with a brand new Haltech EMS through myself. I'm guessing Ben's bill for repairs would be in that neighborhood and he's still using stock electronics that are known to be problematic.

------------------
Chris Ludwig
08 ITS RX7 CenDiv

[Guest_Benspeed_*]

Originally posted by C. Ludwig@Aug 4 2005, 10:34 AM
This is just reason #325 that I feel the ECU rule should be opened up to allow free reign of modification to the electronics and the wiring harness. For $1500 someone can purchase, have installed, and have a baseline tune with a brand new Haltech EMS through myself. I'm guessing Ben's bill for repairs would be in that neighborhood and he's still using stock electronics that are known to be problematic.

------------------
Chris Ludwig
08 ITS RX7 CenDiv

49236



The bill was north of that, but very reasonable considering how much work was done. I would think that a Haltec would make life infinitely easier working on these cars.

Not only did Flatout set me right - I won my first race this weekend. The setup I got from Flatout had me hooked up!

[Charles Buzzetti]

Well this topic could not have come at a better time.
I raced at Laguna Seca last weekend and experienced limp mode and high RPM breakup (at different times) in my 89 ITS for most of the weekend. I changed coils, CAS, ECU, AFM, plugs and wires. Only to have these problems come up at different times during the weekend.
I ended up turning the key off then back on while driving and the problem would clear up until the next lap at the same spot.
I had the fastest lap of the weekend for ITS by .78 seconds, just could never get the car to run clean for a whole session.
Now I at least have an idea of where to turn.
Thanks for the info.

Charles Buzzetti

[tims90rx7]

Congrats Ben! You da man! :happy204:

I knew it was only a matter of time. See you at NHIS soon.

[benspeed]

Originally posted by tims90rx7@Aug 11 2005, 03:04 AM
Congrats Ben! You da man! :happy204:

I knew it was only a matter of time. See you at NHIS soon.

58216


I'll be up for the September double - you got your chance to retake second in the points during August!

Looking forward to that double - I'll come up for the test day to see if I can get down into the 14s. :smilie_pokal: