Engine Stubling Issue / Hard cold start

[JTurbo]

Problem is with my 86 SVO, it's mostly stock. Car has had a cold start problem for a while now. When it's below ~35°F ambient temp and I go to initially start the car, it will start but will barely idle for apx 1 or so minutes. If you try to rev the engine during this time, nothing happens (stays at ~1k RPMs). Once the car is warm (or the ambient is warmer than 35), the car starts normal and will rev properly. ECT? VAT? there are the only two sensors that I can think of that would affect cold starts....

Next problem - the car doesn't seem to have the proper amount of power (this from my butt-o-dynometer). It "feels" like the car is running lean / pulling timing. I have to keep the car in "premium" mode to get any sort of normal operation. Put it in regular mode and it runs like crap. This is the reason why I'm thinking the car is pulling timing. I'm guessing that in premium mode there is less timing to be pulled and the car seems to run normally.

If I drive like grandpa (don't rev past 2700 RPM) it drives basically normal. But if I try to get on it, the engine sort of falls flat. Also between shifts the car will "buck" initially then even out. Again, I envision the car going slightly lean during the up-shift period then once the PCM figures out that the engine is not lean, the power will even out and pull a bit normal.

New/recent tune up. New {stock} fuel pump back in the fall of 2010. New fuel filter last fall. I've got 39PSI at idle (with vac ref removed, 32 with the vacuum connected). I just ran it with the FP gauge visible through the front windshield and I'm getting adequate FP increase with boost. So I think the fuel system is functioning correctly. However, when I first connected the gauge and went to start the car, the pressure only went up to 20psi. Did key off and on again and it went up to 40ish PSI and held. Weird???

I also read that on the 86 there is a vacuum operated switch that affects the FP voltage. I tested mine and it seems to work properly, apply vacuum and the circuit opens. Not sure exactly how this affects the fuel pressure. However for haha's I am going to bypass this switch (so it's always closed).

So that leads me to why the car seems to fall flat. Could it be related to the knock sensor? Is there a procedure to {easily} test a KS?

I haven't ran codes on the car yet (got a genuine code reader on the way - tired of using the old test light method). Going to double check the base timing, I'll report back on that shortly.

Any thoughts or recommendations on where to look next?

JT

[brsvo]

How old and what octain is your gas? Have you tried turning the key on and off a couple of times before cranking to build fuel pressure? You can just disconect the KS'er to check if thats causing problems, but listen for pinging blown head gaskets are no fun. How long does your fuel pressure stay up after you shut down? Maybe a leaky FPR?

[MikeFleming]

My frst thought points to fuel flow. What is FP during that low-temp cold start for that first minute?

BTW - Premium mode adds six degrees MORE advance than regular mode.

[caroth]

What about cam timing, have you checked to make sure the belt hasn't jumped a tooth?

[JTurbo]

Last night I checked the timing and it was waaaaay off. Set it to 10° initial/base and it's running much better. Imagine that!

Cold start isn't an issue any longer either.

I had the timing belt off last fall when I replaced my lower main crank oil seal. Threw the belt on and never checked the timing (started right up, so I figured it was A-Ok). Lesson learned....

Thanks for the responses.

JT

[dznj]

Well it is great when it is something easy (and inexpensive!) to fix!!!:D

[BLK BRD 88]

Last night I checked the timing and it was waaaaay off. Set it to 10° initial/base and it's running much better. Imagine that!

Cold start isn't an issue any longer either.

I had the timing belt off last fall when I replaced my lower main crank oil seal. Threw the belt on and never checked the timing (started right up, so I figured it was A-Ok). Lesson learned....

Thanks for the responses.

JT

It's so often those most obvious & simple little things that we tend to overlook, that cause us the most trouble!
Ron

[TheSVOTrust]

Last night I checked the timing and it was waaaaay off. Set it to 10° initial/base and it's running much better. Imagine that!

Cold start isn't an issue any longer either.

I had the timing belt off last fall when I replaced my lower main crank oil seal. Threw the belt on and never checked the timing (started right up, so I figured it was A-Ok). Lesson learned....

Thanks for the responses.

JT

This the the difference in a true OWNER that started at the right place and fixed WITHOUT throwing parts at car ! It allowed you to "think back" - to what you did (the belt) and review your work! Good for you - there is much to be learned here for the new 2.3EFI T/C owner !! So often (because they ALSO WANT TO GO FASTER) they go down a path the REALLY fubars the car.

Anyway, glad you got it posted the findings and informed us!
Mark
P.S. Many never update or "admit" a mistake.

[JTurbo]

Thanks Mark. Weird thing is that the timing must have been an issue for a while (way before the timing belt removal last fall) because all last spring and summer the car felt lethargic. I was thinking there was something "electrical" with the EEC-IV and/or a related sensor(s). Car is definitely running better and is once again a pleasure to drive.... The SVO gods are smiling!

JT