Originally Posted by et cetera (Post 12238738)

I have, starts right up and idles. Anything I do that leans out the mix at start seems to have a positive impact.

Originally Posted by mysocal911 (Post 12238850)

Next check the fuel pressure and the vacuum lines going to the regulator & dampener for leaking fuel.

Originally Posted by et cetera (Post 12239025)

The fuel pressure had tested in range, but I could smell fuel in the vacuum line connected to the regulator. It was never wet, just a slight fuel smell. I went ahead and replaced the regulator anyway. None of the symptoms changed.

Originally Posted by mysocal911 (Post 12239166)

And you checked the vacuum line to the fuel dampener for leaks?

Originally Posted by et cetera (Post 12239025)

The fuel pressure had tested in range, but I could smell fuel in the vacuum line connected to the regulator. It was never wet, just a slight fuel smell. I went ahead and replaced the regulator anyway. None of the symptoms changed.

Originally Posted by et cetera (Post 12217350)

This issue has been driving me a bit crazy and has me running in circles. Rather than continue to throw $100 at it each time I blindly replace a part I wanted to get a few other opinions before my next step.

Symptoms:

• Starts when cold and immediately dies
• When running it has short power cuts during hard acceleration
• Wants to die when taking off from first gear, need to give it plenty of throttle to get going or it will die
• The idle is just over 1100k RPMs and does tend to "bounce"
• Occasionally, when I go to turn the car over the key feels manually locked out of the start position. After taking the key out and trying again it works after a few times.

Other Facts:

• If I give it a little gas while starting it will eventually find an idle and warm up.
• While its idling, and still cold, if I even look at the throttle to soon it dies.
• It warm starts just fine.
• Separately, I can jump the CHT at the female connector and it fires right up and idles at 800 RPMs. It does run a little rich in this situation as indicated by small amounts of white smoke.

What I've done so far:

• I purchased this motor rebuilt by a previous owner, many items were replaced with new, specifically the fuel injectors had been cleaned and the fuel lines refreshed.
• All new Plugs, Cap and Rotor, fuel filter(No Change)
• Cleaned and bench tested the ICV (No Change)
• Replaced the Idle Control Microswitch (No Change)
• Replaced the Cylinder Head Temp Sensor (No Change)
• Swapped in a known working Coil (No Change)
• Fixed a minor vacuum leak at back of Throttle Body (No Change)

... and thats where I'm at today. I have a friend who is going to let me plug in my DME into their working car to rule that out, but I'm not sure where to look next.

I read through a bunch of threads on the various subjects. Based on those I am looking into a few other items, but I'm not convinced they are the issue.

DME Relay - I get power to the fuel pump. My understanding is it wouldn't even start if this was the issue, but I may be wrong.

Crank Position Sensors - They are gapped correctly. I do have an over the transmission oil line from ER that runs near them, not sure if that could cause problems. My understanding with these is also that the car wouldnt start at all if they had failed.

Throttle Position Sensor - This would explain the hesitation under power, but I dont believe it would impact the cold start and idle.

Anyhow, I think thats everything I've done to this point. I'd love to hear your thoughts or just some words of encouragement so I don't give up. :)

Originally Posted by mysocal911 (Post 12239287)

So, the engine has never run properly since you received the "rebuilt". This is significant!
Since the injectors were sent out and "cleaned", you really don't know the real state of the injectors, e.g. are they even the correct ones.
Hopefully, they are the low impedance (1-2 ohms) injectors. Obviously, the wrong injectors will cause problems like you're having.
Have you measured the temp sensor at the DME ECM connector, i.e. pins 13 & 5?

Originally Posted by et cetera (Post 12239288)

Yep, I checked those before as you instructed.

Pin 5 was properly grounded.
Port 13 read 1.67v

Originally Posted by et cetera (Post 12239288)

I bought it from reputable users on these forums. I have no reason to believe they are anything but reconditioned OEM injectors.

Originally Posted by et cetera (Post 12239288)

Separately, I can jump the CHT at the female connector and it fires right up and idles at 800 RPMs. It does run a little rich in this situation as indicated by small amounts of white smoke.

Originally Posted by mysocal911 (Post 12239305)

[B]

When warm, the temp voltage should be less than .50V.



Did they ever run the engine? There's basically nothing else except the DME ECM.
Did they supply the ECM? If not where did it come from?



If the temporary fix is that simple, it usually indicates the wrong injectors or the ECM, assuming all your other tests were done correctly.

Originally Posted by et cetera (Post 12239367)

The motor had been run, and tuned. To my knowledge it’s the same ECM that the car was tuned on.

I can check the warm output for the CHT sensor, but I really don’t think it’s that as my issue is primarily with the cold start.

To try and be more specific. The problem seems to be that the car starts and can’t “catch” the idle as it drops down. So it immediately dies. Occasionally it gets close, and will fire a few extra times before dying.

That would lead me to the idle switch, but I have two of them which both test fine. I did test the EMC on another car but who knows, maybe I just got lucky when plugging it in that car.

I’m gonna do another vacuum test in the morning to see if that returns anything.

Originally Posted by mysocal911 (Post 12239383)

So if that's the main problem, and you can prevent it from dying by opening the throttle. Then it's a simple idle problem
unrelated to a rich fuel mixture. But you mentioned up-thread that it will start OK if the AFM is disconnected, which doesn't
correlate with this last post.

Hopefully now the thread has converged on the real basic problem, a momentary bad start-up idle!

Originally Posted by mysocal911 (Post 12239383)

So if that's the main problem, and you can prevent it from dying by opening the throttle. Then it's a simple idle problem
unrelated to a rich fuel mixture. But you mentioned up-thread that it will start OK if the AFM is disconnected, which doesn't
correlate with this last post.

Hopefully now the thread has converged on the real basic problem, a momentary bad start-up idle!

Originally Posted by et cetera (Post 12239525)

To be even more specific. I just started the car and kept my foot on the gas. I need to do that for a solid minute for the car to warm up. If I take my foot off the gas too soon it dies. I try to keep it at 2k rpms during that time, but it will bounce all around even when I’m not changing my input.

Originally Posted by et cetera (Post 12239638)

I reached out to the person I purchased the motor from, turns out the DME is not the one that originally came with the motor but one that had been in another car of his. So the custom chip in there wasn’t for this motor.

I’m gonna start by trying to reset the idle. I’m also going to try and source a stock chip.

Originally Posted by et cetera (Post 12239638)

I reached out to the person I purchased the motor from, turns out the DME is not the one that originally came with the motor but one that had been in another car of his. So the custom chip in there wasn’t for this motor.

I’m gonna start by trying to reset the idle. I’m also going to try and source a stock chip.

Originally Posted by proporsche (Post 12239884)

you know there is an adjustment on your DME for fuel quality.....

Ivan

here

https://www.911chips.com/fuelsys.html

Originally Posted by et cetera (Post 12240191)

Took a look at this today. Found it was in position 5. Turned it back to 0 but it didn’t have any effect.