Cleaned up ignition system now engine wont idle or go above 3500rpm.

[FiIiAiT2000]

So a couple days ago I decided to clean the contacts and wires around the ignition coil and module on my 1981 FI spider. I also undid the hoses for the idle air bypass valve system and re-tightened those back on at the same time. Now that I've plugged everything back in the engine will only idle for a short amount of time before sputtering and shutting off. I managed to keep the engine running at about 2500 rpm with the throttle, but when I went to about 3500 rpm the engine started cut out again and seemed like it might be misfiring. I heard a loud ping so I stopped immediately. I'm not sure what could be wrong. I've double checked that everything is attached correctly, and I'm kind of at a loss as to what could be causing the problems. The engine ran fine before I cleaned up the contacts around the coil and tightened the hoses on the bypass valve. I'm thinking it has something to do with the ignition, but I'm not sure if it's the coil or the control module, I'm 99% sure everything's plugged in at the right place, just wondering if you guys have any idea where I should start looking to see if something's broken or attached wrong. Thanks!

[bradartigue]

Hard one - because the problem is in whatever you touched. Go back and check and test everything you touched when "cleaning up"

[vandor]

A large vacuum leak could casue those symptoms.

[spederman85]

I've been reviewing posts to see if someone has experienced similar issues as mine, and this seems similar. My 80 FI does not idles until she warms up, then runs fine. However, it does seem to miss as about 3000 RPM, mostly when decelerating. I saw the suggestion that this could be from a vacuum leak. How would we go about testing that?

Thanks

[4uall]

this might help

https://www.youtube.com/watch?v=zMok2y05jNE

[FiIiAiT2000]

Time to buy a cigar haha. Thanks I'll check for vac leaks. I also undid the air intake but I'm sure I tightened everything back on. Could the vac hose running to the distributor cause a large enough vac leak just by being a bit loose? Cause the fit doesn't seem that tight and there's no clamp on it.

[FiIiAiT2000]

Okay so I couldn't find any obvious vac leaks. The engine won't start any more. It turns over and seems to fire a little but won't run. The things I took apart and reassembled were the air intake hose, the idle air bypass valve and hoses, the vac hose connected to the distributor and the ignition coil and connecting wires. Nothing else was changed and I believe everything is in the right place. Could this be caused by the hoses being old and leaking? They are all original.

[bradartigue]

Okay so I couldn't find any obvious vac leaks. The engine won't start any more. It turns over and seems to fire a little but won't run. The things I took apart and reassembled were the air intake hose, the idle air bypass valve and hoses, the vac hose connected to the distributor and the ignition coil and connecting wires. Nothing else was changed and I believe everything is in the right place. Could this be caused by the hoses being old and leaking? They are all original.

You'd have to have a pretty bad air leak for it to not run. Get a voltmeter and start testing things, ignition system first.

[FiIiAiT2000]

Problem solved. Letting contact cleaner sit in top of ignition coil = bad idea. Poured out more than a couple drops when I unscrewed the little screw on top.

[FiIiAiT2000]

Sorry to ressurect this topic, but have since realized that it was probably oil that came out of the ignition coil when I unscrewed the top. Anyways the car still won't idle. It fires for a second then dies. Tested the ignition coil and bought a new one as well (Accel 8145 Breakerless) both showed ~9800ohm between secondary and primary. Heat sink mount is fully grounded now. Anyways I'm gonna pull the plugs and check for spark then go from there I guess. The engine will sputter for a couple seconds sometimes, but I wouldn't call it an idle. Just not sure what could make the engine go from running to not running just like it has.

[RRoller123]

Mine very recently exhibited this exact behavior. Turns out it was running only on the CSI, which lets it start/run for a second or two, but no more. I had left one of the ground wires at the intake plenum unattached, which will cause the injectors not to fire.

[FiIiAiT2000]

Oh okay yeah I'll check those out, thanks.

[FiIiAiT2000]

Okay so the grounds on the intake plenum are good. Definetly have spark. So I think it must be a fuel issue. Does CSI stand for cold-start ignition? Your problem sounds identical to what's going on with my engine.

[RRoller123]

The CSI is the Cold Start Injector, located up on the front end of the intake plenum. You can put a FI fuel pressure gauge on a T there to check fuel pressure, I think it should be around 38psi but don't quote me on that.

The best thing to do is to get a good FI Manual and step through the various diagnostics. I bet the solution to the problem makes itself apparent quickly.

Here are a few Fuel Injection Manual sources and references from one of my earlier posts, plus, Brad Artigue's new book has a very good section on this topic:

For those interested in studying the Bosch L-Jetronic system, there is an amazing amount of quality material available on the web.

This link from the BMW folks has a very good PowerPoint type presentation on the components, etc.

http://www.firstfives.org/faq/ljet/jetronic.pdf

This one, from the VW folks, has a good component description too, but also a good trouble shooting manual:

https://www.type4.org/manuals/ljet/

Here is Bosch's own manual, a long, detailed slog through the swamp for sure. Probably best printed out for studying:

http://foxed.ca/rx7manual/manuals/BOSCH ... Manual.pdf

[wizard124]

My suggestion:
Consult a wire diagram and re-check you have all the coil leads correct.

One of those leads runs to the ECU. That input into the ECU is used to shape the pulse which fires the injectors. It sounds to me that your problems lies here.

Next, check for a broken wire to the ECU. Use an Ohmmeter with extended leads. The wire diagram will tell you the color wire and plug number at the ECU