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my ITA 89 240 Sx is experiencing some form of intermitant ignition problems - above 3000 rpm the tach bounces wildly sometimes over the rev limit. At the same time the iginition appears to be cutting out and the motor backfires - as a consequence we can't make power. This caused us to pull from the grid at NHIS this weekend. We pulled and changed the distributor, cap, rotor and igintion coil to no avail. ANY SUGGESTIONS WHAT NEXT? HELP
Sorry to see you leave on Sunday morning. It was nice to meet you this weekend. Good luck with the car. I was talking to someone about your issue, and they suggested a faulty computer? Any chance you got a spare to plug in?
My 240 started running bad on Sunday, seems the battery light was on, and it wasn't pulling as well as on Saturday. Tach would jump a little at 5500, but also seemed to stutter at that spot. I'm think altenator or loose ground. Anyone have any other ideas?
Jeremy
[This message has been edited by 7racing (edited July 20, 2004).]
Maybe check the crank sensor? It could be bad, loose, cracked, etc.. Just a thought.
This may or may not help but I was advised to take measures to keep heat away from the distributor on my s14 so we built a heat shield to protect it. I'm not sure if your distributor is even located in the same place as ours but this may help.
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David Murphy
Murphy Motorsports
Memco...
A couple of questions on your problem. Has it ran fine before? New engine? Any engine repairs/modifications since the last time on track?
Grounds are a good place to start looking. When you said distributor was replaced, do you mean the whole thing, including the crank sensor?
Jim
Jeremy, call me dave
Guys thanks-
A few answers to some of your comments
Engine is not new, came from salvage- ran two test days plus two days of licensing school in April - ran fine
Removed entire distributor - shaft, splined gear, whole assembly, seemed fine, replaced with spare which came off other motor (which dropped valve last year at July DE at Nelson ..another story)
engine does run hot - will shield distributor
but why problem only above 3000 rpm?
Some have suggested ignition relay
Mem,
I race a 12 valve for several years. I never had the need to install the heat shield. I know several who did make one for their cars though. Have you tried to check the ECU for any codes?
pure speculation here....Is the ignition's goofy stuff at 3000 rpm similar to hitting the rev limiter? Maybe the ECU is seeing a faulty signal which makes it think it is overrevving..hence the erratic tach signal...maybe...
Jim
well did u get it solved...Would like to know what the problem was in case we experience something similar..thanks Chris
It doesn't sound like the same problem I just fixed, but for what it's worth I'll tell you the problem I had and what fixed it.
I was not getting any ignition advace at all- the car ran ok (not great). Without the advace I bumped the idle advance up and ran it - it ran ok up to 5k rpm and ran out of timing.
We tried everything - new harness, new distrib. new relays, new computers.
The fix - after getting to the end of the trail, and about to change out the dash harness - I decided to try the ignition switch. I had bypassed the ignition to a starter button and toggle - because I picked the car up at auction (no key). I pulled the ignition out of a parts car (with key and swapped it on. It worked - I now have advance and the everything seems perfect. The lesson - those two wires going to the bottom of the key side of the ignition lock are an integral part of the timing/ecu circuit. The key completes the circuit. I know this doesn't fix your problem - but I thought it was a good place to share this info.
Jason.
DC Region MARRS
1989 240sx ITA #21
Interesting problem. I'm not intimately familiar with the KA engine, but am pretty familiar with the SR. Nissans of the same vintage use similar parts, so I'm going to throw out some ideas.
First of all, the problem kicking in at 3k is interesting because the ECU has a limp mode that keeps the engine from revving over 3k. Are you running a modified ECU? Is it a JWT? If so, you may want to call JWT. Chances are they will have a good idea what is going on.
Have you tried another ECU?
Have you modified your ECU in any way (besides getting a JWT)?
Other things to consider:
Bad MAF
Bad TPS
Does the KA have a power transistor?
When you replaced the distributor, did it do exactly the same thing or did it change?
The crank angle sensor is in the distributor of the KA isn't it?
My money would have been on the distributor. But, since you changed that (assuming the exact same symptoms), I would look towards the ECU, MAF, or Power Transistor (if it has one).
If you haven't tried a new ECU, I'd do that first.
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George Roffe
Houston, TX
84 944 ITS car under construction
92 ITS Sentra SE-R occasionally borrowed
http://www.nissport.com
Guys,
We found the problem to be a bad ground - once we cleaned and tightened it the car ramped through 6000 rpm with barely a hick-up. It ran well under load at a test day. The ground that we are talking about comes off the harness that runs to the throttle position sensor - on my car its actually threaded to the air bleeder port on the manifold - it seems to only like this location too as we tried a spot on the block which it did'nt like....
so of course we ran it on saturday at NHIS but for those of you not there - the rest of the story is the engfine overheated after a prolonged pitstop for a clutch adjusted and we warped the head HAH!
remember that the "IT" in ITA stands for "infinite trouble...."
thanks for all the help and advice in this thread - look for the next thread being the "care and cooling of KA motors....."
Take a lok at my brothers nasty huge massive radiater & cooling fan. Next problem ,he lost injector pulse on sat practice. We changed the ECU & have the exact same issue.Is there a crank & camshaft position senser in the distributer? It seems wierd to lose pulse on all 4 injecters at once according to the schematic. Ther is power at all 4.
Dano
77 ITA RX-7
77 ITA Miata
(obviousley a Mazda tech)
Memco,
You absolutely have to keep these things cool. They will melt holes in the heads and pistons, and do all sortsof other bad things if you don't. I had a large by huge aluminum radiator and a Setrab Oil cooler the size of a honda radiator (ok..not quite). Mine always ran cool(180ish), even in Florida summers after that. The only thing it didn't like was idling in the paddock after coming off the track. As long as I kept the revs up, no problem though (throttle blip to 2500-3000).
Don't use a cheap oil cooler,they restrict air flow. Don't mount the cooler to the radiator with the common zip tie things that go through the radiator core. Watch oil and water temps.
I have pages of notes I will forward if you want. Some of them are from a very reliable resource---the rest are from me.
Jim
Heh, yeah, but don't look at the fan that really isn't there. http://Forum.ImprovedTouring.com/it/wink.gif It is a huge radiator, though, and as long as air is flowing through it, then I'm fine. When we first started it up with the new motor, we had lot's of cooling issues. First test day on track and haven't had an overheating issue since....weird.Quote:
Originally posted by Dano77:
Take a lok at my brothers nasty huge massive radiater & cooling fan. Next problem ,he lost injector pulse on sat practice. We changed the ECU & have the exact same issue.Is there a crank & camshaft position senser in the distributer? It seems wierd to lose pulse on all 4 injecters at once according to the schematic. Ther is power at all 4.
Dano
77 ITA RX-7
77 ITA Miata
(obviousley a Mazda tech)
Anyway, yeah about the (lack of) injector pulse. Could this be the same ground that Memco is talking about? I'll check out the TPS tonight when I go to charge the battery (drained it too much over the weekend trying to get the damn car started). I have no injector pulse, and most posts in other Nissan boards say CAS or computer. We tried a computer and I put a new distributor in last night. Hopefully that cures it.
Anyone else have any ideas?
Jeremy
Jeremy, I was eavesdropping when you were talking to Matt Saturday night, and it sure sounds like a bad ground. We had a nearly identical problem with my NX2000 last year, and the problem was...ta da!...a bad ground. If these computers don't have a common ground reference, either through a bad or missing ground, then the voltages and sensor values get screwed up. All it takes is one good rain and a poor ground becomes a bad ground.Quote:
<font face=\"Verdana, Arial\" size=\"2\">Anyone else have any ideas?</font>
I recommend breaking out the FSM and tracing all ground wires and cleaning up their terminations. Also make sure that the chassis-engine-battery ground straps are in good shape.
GregA
The car had a good size custom aluminum radiator with dedicated fan on it - we must have lost just enough during our stop to adjust the clutch to have created a void somewhere - got a line on a engine.. so here we go again!
Other suggestions on bad firing have been the throttle sensor and mass flow meter if you go to the fault chart in the manual i think it leads you to the throttle sensor ....
ITS66 i'd appreciate your notes you should be able to contact my email through the profile if not reply through here
Memco,
Email addresses don't show in the profiles here, even if you turned them on. Why don't you send me a message to jcohen<at>wdi.com Soem of this stuff is pretty lengthy.
Jim