No Spark!

[jimbbski]

I have a 1988 Scriocco 16V with CIS-E.
Had a head gasket let go a few weeks ago. Swapped out the engine with another one I had. When I tried to start it I got no spark! I double checked all my connections. I have the Bentley book and have done some of the checks they listed.

Just wondering if there are some tips or tricks some of you may have that you can give me. I will continue going over the ignition system and the tests the Bentley lists.

I don't see why it shouldn't start? I have swapped the Dist. with another. I checked the timing, lining up the crank with the cam, with the dist. Pulled a plug wire and inserted a spark plug and grounded it and then cranked the engine. No spark. Did a coil check and that was OK.

Is there any way to confirm that the ECU is working as that is the one thing that controls the entire ignition system.

[Sandro]

Any chance you have or can get another wiring harness?

Similar thing happened a few years ago. Went crazy checking everything, and turned out with the wires being old, one from the control module had broken internally. $5 from the junk yard solved the problem.

[jimbbski]

I thought of that but don't want to go there. I would rather check each wire for internal breaks and replace that wire then the whole harness. Another harness would be just as old and subject to the same problems.

I haven't worked on it since I posted but will get back on it today and hope I find the problem.

[Flyinglizard]

Check the ground wire from the module and the computer. 2 or 3 go to the end of the head. MM

[Lael Cleland]

The big brown wires that bolt to the rear of head, tranny side are computer grounds.. I have seen loose or broken wire at battery cable end cause this.. make sure its out of gear when you do the wiggle test, I have had VWs start just by touching the cables.... After cranking a bunch, fuel in cyll, touch a cable end and SPARK! I was almost run over a month ago by my GTI.. Luckily my fuel pump was off, and it didnt get far... LOL..

Is there a pulse at the coil? Power at both sides with key on? Crank it and stick a test light on the - or + side of the coil, one side should pulse. If no, make sure the dist is getting 12V. If yes, probe wires to dist and make sure you are getting a pulse when cranking.. Generally the ign switch is the first place to look if you dont have power on both sides of the coil, but prollie not this case..

I have seen 1 knock box fail in 20 years of vw repair.. Lots of distributors(broken wire at the PU coil), 3 ign module, but hundreds of broken wires in the ign system..
Those 16V are notorious for the alt & A/C compressor bolts falling out or breaking off, at 4000rpm they vibrate like crazy, all the wires are vibrating also. So you touch them and they break...

[Conover]

You have a test light?

Check signal to the coil. Test light on positive terminal of the battery to the negative side of the coil. as your cranking the engine it should flash. No flash check the Ignition Module, do have flash, change the coil.

[Flyinglizard]

Con, I always assume that the main power has been checked..
Just turning the power on and off will trigger a spark @ the coil, if the power supply and ground are valid.

[jimbbski]

Been off the net for a while, a problem with my computer.
The lack of spark was due to a back ground on #2 wire from the Ign. Mod. to ground. I fixed that and got my spark back.

Then the engine only would start and then die. I found that the air meter seemed to be the problem as I wedged it slightly open with a plastic tywrap and the engine would then idle. That's as far as i got when an oil line let go and I ended up with oil all over everything! I had tighten an oil line to the cooler and this caused the line to shift a bit and come in contact with the cooling fins on the alternator.

Do you know that those fins will cut right through the SS braid on a -10 aeroquip hose!

At that point I just cleaned up the mess and let the car sit.
See my other posting.

[joeg]

good grief!!

[Conover]

Con, I always assume that the main power has been checked..
Just turning the power on and off will trigger a spark @ the coil, if the power supply and ground are valid.


:017:

Not talking about the power, I'm talking about how to check for actual signal at the coil, same applies for electronic fuel injectors and many other parts. You can tell if there is a square wave present on the signal wire with a simple test light hooked to the positive side of the battery.

[Flyinglizard]

SSB or SSC for you..

[jimbbski]

Further update.

I started the car yesterday and it ran. Once it warmed up a bit it idled good. When I went to rev it the engine speed came up but it seemed like it was running lean, sputtering, missing, etc. This whole thing is just plain weird.

I have a head gasket let go, I change the engine and now all these problems! The engine was running fine before. I just don't get it.

There is nothing wrong with the engine mechanically, I'm using the same injectors from the other engine as they were all new. I have to assume that there is still something wrong electrically.

When the head gasket let go some oil & water was blown back through the intake system as the air filter was soaked with this mixture. If the air meter moves freely, and it does, how could the air meter cause these issues with smooth running? Especially since the old engine ran very well before the gasket went. I didn't disconnected any fuel lines to do the engine swap other then the fuel feed line to the filter and then only after I had problems with it not running correctly.

[Flyinglizard]

Check the cam timing, at both points,( cam to cam and cam to crank.)
MM

[jimbbski]

Check the cam timing, at both points,( cam to cam and cam to crank.)
MM

That is all good. The head was removed from the engine before I installed the engine. This engine sat for 5+ years so I wanted to check it out first. I then installed the head with the cams rotated to their correct TDC marks with the engnine at TDC too.

The issue is in the fuel injection, the fuel mixture at anything above idle is off. I have not adjusted the CO screw which was suggested to me to do by someone off line. I want to verify that all other systems are working correctly first before I do that.

[Lael Cleland]

check the wires under the boots @ the potentiometer & DPR.. they also break... and vac hose to knock box..