Delayed throttle

[Bitsyncmaster]

I forgot to mention this owners car also has the wideband setup that I have. So it only takes about 20 seconds for the lambda system to got closed loop after a cold start.

So since it's cold this morning (45 deg. F), I opened my cars engine cover and the garage to let it cool down so I can do a punch throttle test on a cold engine later this morning.

[Bitsyncmaster]

Here is a video of my DeLorean cold start.

https://youtu.be/U5jR4KCCbE8

My car had not been started for a few weeks. Garage was open for a few hours with outside air temp at 45 deg. F.

I did get a couple backfires punching the throttle. I never punch the throttle so quickly so never knew it would back fire. Not really concerned with that condition.

Sounds like I need a valve adjustment since I hear it ticking running that cold.

[David T]

Here is a video of my DeLorean cold start.

https://youtu.be/U5jR4KCCbE8

My car had not been started for a few weeks. Garage was open for a few hours with outside air temp at 45 deg. F.

I did get a couple backfires punching the throttle. I never punch the throttle so quickly so never knew it would back fire. Not really concerned with that condition.

Sounds like I need a valve adjustment since I hear it ticking running that cold.

The CPR won't make a cold engine run like a warm engine. Till it warms up it will stumble a little and not run as smooth. Before getting out all of the test equipment the best tester you have is your 2 eyes. Examine all of the vacuum hoses by the CPR and the vacuum advance. Make sure the vent hose on the CPR is not kinked or plugged up. Since we have seen these symptoms before we can narrow down the initial problem area to the systems that are active during warm-up. Till they are proven good it is best to confine the testing to ONLY that. Otherwise you will go off on tangents and disturb other things that may not need to be messed with and may introduce other problems.

[Jonathan]

Here is a video of my DeLorean cold start.

https://youtu.be/U5jR4KCCbE8

My car had not been started for a few weeks. Garage was open for a few hours with outside air temp at 45 deg. F.

I did get a couple backfires punching the throttle. I never punch the throttle so quickly so never knew it would back fire. Not really concerned with that condition.

Sounds like I need a valve adjustment since I hear it ticking running that cold.

Hey Dave, this could find its way into another thread it if gets us too far off track, but after seeing you not have an idle microswitch in place where it normally would be, what all modifications do you have to your car that aren't as originally designed or stock?

Robert made a good point about the time-out or going about troubleshooting in a methodical way and knowing what you are dealing with, and part of that would be knowing not only the condition of the car, but also what changes are in the car that are different from the factory.

I realize the original intent of the thread was on a friend's car, so how yours behaves is a separate issue, it just made me think about how sometimes we skip over differences and that piece of information could be key in figuring out a problem on a car.

I know when I see a thread asking for help on a carbed or EFI car, I generally keep quiet if it's in an area I know differs from stock (due to my lack of knowledge on those set-ups). Not just engine swap differences, but the upgrade modules you sell and other things (like understanding why there isn't an idle microswitch on your car) can get a lot of guesses going in directions they didn't need to go.

Just a thought anyway. I think I'll put together a list of what isn't factory on my car, plus things that are upgraded or have had recalls done, just to remind myself/others what the starting point is. Might put it in my forum signature depending on how long it is.

[Bitsyncmaster]

As stated, both cars have wideband. That results in closed loop lambda in 20 seconds of running. Since both cars have the stock WUR which make the mixture richer when cold, the lambda would be trying to lean the mixture to 14.7 AFR. Now weather the lambda can overcome that very rich mixture when cold, I have not tested. Both of us have cut the thermister/WOT switch wire that was going into the lambda ECU

Both of us also have my RPM relay.

My car has the hot start relay running without the thermotime switch connected.

My car also has my idle ECU and right now I have no deceleration valves.

Of course I have all solid state relays but those should not affect these tests. My primary pressure is shimmed to 75-76 PSI. Hot mixture is set to stock dwell values. I don't have the idle switch so advance goes on above 1500 RPM. The stock unit would hit advance a little sooner. I have no WOT switch since I have a console switch for selecting a richer mixture (think it's set to 13.2 AFR). My video test was done with lambda set to 14.7 AFR.

There is no vacuum advance on a cold engine anyway.

I wonder how a stock setup would work punching the throttle on a cold engine (air cleaner removed). Anybody care to try?

[Ron]

Dennis,
We're usually on the same page, but I'm not even following your response(s):

What IF the thermal vacuum control valve was bad (stuck in the closed position) since 2008 or someone connected the hoses in the wrong orientation.

You would never see vacuum to supply the enrichment circuit.

I agree, being why I said "Thermal Vacuum Switch (hung at warm position/not getting supply/etc)" in my first post (#4)??

Once the engine has warmed above the threshold where enrichment was needed it would run normal.

I agree. But it does??
The OP says, "My friends DeLorean has a cold engine delayed throttle response. When the engine has warmed up the problem goes away." To me it had Cold Acceleration Circuit written all over it...resulting in my 1st post in general, which seems obvious even when I re-read it, so I at a loss here?? The last thing I want to do is confuse someone (where I'm at now ;-)

It seems like that valve has a low failure rate but it is possible.

Agreed. But, fwiw, I had to call Julee and order one for mine last month (both ports passing ), Chuck's and Jim's earlier (stuck in COLD position).

Maybe this will help - My only purpose in the post you quoted was to quote the manual to correct a misstatement related to the problem....

[DMC5180]

Ron,

Sorry, I missed seeing your # 4 post.

I realized you were just correcting the previous line quote. I went back to the manual to verify how the vacuum switch functioned before making my previous post.

And then there is this auto correct feature on my phone that changes words after typing something that I fail to catch with a quick scan proof read.

Sometimes my thoughts are a bit disconnected. I'm get old

[Ron]

No problem bud! It seems I got under Robert's skin somehow with the same post. ..and Rob's the other day???
Yeah, I can relate -- I've done been old. To old for this $hit!

[Ron]

Then you know what? My mistake. I must have been thinking of another CIS application where the vacuum feed to the CPR is NOT affected by engine temperature. Such as the 5 port configurations.

Um,...five lashes with a wet noodle!?!
Mine has 5 ports, but only 2 have vacuum feeds. (That's one on me, since I have seen some with less, but not more ;-)

That still does not change the fact that a methodical testing procedure NEEDS be initiated here rather than simply chasing ideas. That leads to twisting and omitting facts in order to suit theories, rather than the other way around so that the truth can be found. And it just seems like in the quest to be the person with the right answer, it has become a competition here to the point where we just want to discount everyone else's input thinking that if only our own is left it will somehow magically become the correct diagnosis by default. It is indeed one of the largest pitfalls of the DIY'er to when asking for help on an amateur forum.

There are a thousand "what if's" here. What this car needs are facts instead in order to properly formulate an accurate diagnosis. That is what needs to be focused on.

No need to convince me. I've been with you on the basics and methodical testing. First post I mentioned the basics, first. And since the cold acceleration enrichment circuit is written all over the OP (going lean, cold), the components/ect the circuit relies on, and vacuum leak(s) that are usually noticeable only when cold. Seems reasonable, if not most likely, right or wrong, imho.
As for the post quoted, as I said above, its only purpose was to quote the manual to correct a misstatement related to the problem....and a suggestion IF he checked the plunger (a good idea imo).

In other words, quit picking on me...at least when we agree

[David T]

I am guessing but the accumulated result of all of the mods makes the motor run leaner when cold. That would negate some of the effect of the CPR trying to run the motor with a richer mixture when cold. That's why you see the pronounced and exaggerated throttle delay effect. Going into closed loop so quickly on a cold O2 sensor is not a good idea, at least put a heated one in so it can warm up fast.