Idle drops every 2 seconds after warmup. Maybe ECU?

[Anarchology]

I'm having this issue come up about 5 minutes after I start the car. This has kept it off the road for now until I fix this issue. What will happen is after the car is warmed up, the idle will dip every couple seconds.

According to the logger (MMcd software), the timing dips from around 12* to 0*. It starts off slowly by doing it once every 15 seconds, but the gap slows over ab out 3 minutes until it is about a second apart.

I went out tonight to maybe see if the ignition timing with a timing gun hoping to see if I could figure it out. The problem is that even when grounding out the connector on the firewall near the battery (to time it with a timing gun), the timing is not steady. It is still moving all over the place as if I didn't ground it out. Hopefully this is making sense to some, since I'm bad at this wording.

I'm wondering if there is a chance there is something wrong with my ECU. Hopefully someone on here has had the same issue and resolved it.

My MODS: Stock engine and turbo, APEXi Neo (flashed to the correct firmware), UEGO widband A/F gauge, stock MAF (removed my MAF Translator thinking it was the issue), Data Logger running MMcd.

Thanks in advance!

 

[steve]

Did you remember to disconnect your datalogger when trying to check/set the base timing?

It grounds the mode pin on the ECU and causes the ECU to be in BISS adjustment mode when you ground the check timing connector.

What is the idle speed normally and what does it drop to?

 

[BlackMount]

Sounds more like a Simple Vacuum Leak Issue or ISC Malfunction; at least the idle dropping issue. idk about the other stuff.

 

[Anarchology]

Did you remember to disconnect your datalogger when trying to check/set the base timing?

It grounds the mode pin on the ECU and causes the ECU to be in BISS adjustment mode when you ground the check timing connector.

What is the idle speed normally and what does it drop to?

That I did not know. I'm going to try that tomorrow then. I'm still having problems with the fuel cutting out. I'm currently adding back some of the vacuum lines I removed. I originally did the simple vacuum line setup that ended up deleting things like my EGR and vacuum canister. Related to this, where do I find the purge control valve. Is this below by the canister?

EDIT: Nevermind, I did find the purge control valve.

Sounds more like a Simple Vacuum Leak Issue or ISC Malfunction; at least the idle dropping issue. idk about the other stuff.

I have two engines, so going to swap out and possibly clean the ISC. Hopefully, this will help out.

 

[And_44]

A bad CAS?

 

[BlackMount]

That I did not know. I'm going to try that tomorrow then. I'm still having problems with the fuel cutting out. I'm currently adding back some of the vacuum lines I removed. I originally did the simple vacuum line setup that ended up deleting things like my EGR and vacuum canister. Related to this, where do I find the purge control valve. Is this below by the canister?

EDIT: Nevermind, I did find the purge control valve.





I have two engines, so going to swap out and possibly clean the ISC. Hopefully, this will help out.

sounds like a good plan.

 

[muddfisher85]

Where was the purge control valve? My 2g is throwing that code havent got around to finding it yet

 

[steve]

What is the idle speed normally and what does it drop to?

Please answer this.

 

[BlackMount]

Where was the purge control valve? My 2g is throwing that code havent got around to finding it yet

If it's the same on the 2G, and I'm thinking of the right thing, is is near the MAF\Airfilter, and has vacuum lines that run to the WGA

 

[Anarchology]

Where was the purge control valve? My 2g is throwing that code havent got around to finding it yet

I know on my 1G it is located under the battery on the canister. I relocated my battery to the trunk, so its easier for me to see it. It might be hard for you unless you pull the battery and pull off the plate the battery sits on.

Please answer this.

The idle in park was normal. It just started to dip down. I believe I found the problem since the ISC had only one screw holding it on with a damaged o-ring. Other than that, I reconnected many of my vacuum lines. I haven't had a chance kick over the car, and probably won't until tomorrow.

The huge problem I had with how this car ran was that when driving it (just around the block) it felt as if I was towing a boat. It barely moved, and it wouldn't go over 3k rpm.

 

[dooblea]

get a vacuum diagram, go over every vacuum line! that is what fixed this problem for a friend of mine!

 

[doayamaha]

Is the car getting any knock on the logger, mabee knock sensor is bad.
Or possible problem with the CAS, also checking the vacume is a good place to start.

As for the fuel cutting when in the rpm is it doing it and at what throttle.