Help With cutting out once car is warm

[bwbolin]

So here is the story. I have an 86 930, mostly stock a few built on’s but that’s about it. The car runs great when it’s under 180 ish degrees. Once it’s up to temp, I starts cutting out, like is not getting enough gas, from 2300 rpm’s up to 3500 rpm’s. Above 3500 it runs out well again. If I pump the gas it will cut out and then push right through into the higher rpm’s.
I tried the easy fixed, fuel filter, plugs, rotor and cap while I was in there. No change. I have chased all the plug wires and looked for loose wiring, no luck. Now I need help. I don’t want to just start guessing and replacing parts. It feels like it’s a fuel issue. But I am not sure where to start. Any help would be great.
Thanks much!

[NathanUK]

Sounds like your ignition is failing.

[WERK I]

I would suggest you have the CIS system checked out. Remember, fuel systems always are set up to run rich on early start up and then return to stoichiometric when up to operating temp. Sounds like a very over-rich condition when the engine is getting up to operating temperature.

As a starter, have you tried a bottle of Techron in a full tank of gas to clean the system?

[bwbolin]

Thanks for the ideas. I have been going through the ignition and everything seems ok in the driveway. I can't check it under load. I guess the next step is injection system.

[NathanUK]

It's well known for ignition systems to work when cold and then as they get hot they start to fail.

I would think an AFR setup would help you here.

[bwbolin]

Sorry for my ignorance. AFR?
After playing with the car for the last two days, then driving it again today, here are some more details. The car runs great as it is warming up. Once it hits about 190-200 the temp starts to drop and it starts to cut out. the problem is much more so in fourth gear then third, more in third then second and not noticable in first. When it is cutting out I get a nice big cloud of smoke out the pipes. It will still push through the misfire and everything then cleans up.
Thanks agian for your help.

[NathanUK]

AFR is Air to Fuel Ratio.

Maybe your fuelling is too rich, either that or it is not getting burnt/ignited.

An AFR setup from Innovate such as the LM-2 would help you to diagnose whats going on although annoyingly IIRC unburnt fuel shows up as the mixture being rich.

http://www.innovatemotorsports.com/products/lm2.php

I have an XD-16 kit.

Have you checked the overboost switch?

[bwbolin]

No I have not looked at the overboost switch I will do that tonight. It dose feel like it is either flooding or starving for fuel. With the smoke my bet is on flooding.
thanks again.

[NathanUK]

If it is flooding, it may be that it is not being ignited due to the ignition.

Good luck!