RPM dropping after WOT

[Vic-GT]

Hi I have decided to post my problem here, after reading many threads I have not been able resolve my issue.

I have a 1993 EP82 with a 4EFTE, CT9, OEM fuel pressure regulator etc.

in other words the car is not highly modified

Current state: the car drops RPM after WOT to the point it stalls and dies, take into consideration this doesn't happen when the car is cold only when it has got into normal working temperature.

Even if I don't accelerate the car to wide open throttle only cruising around the RPMS will drop not to the point it stalls and dies but they do drop to 500 - 600ish

all this happens in conditions where I have to drive the car fast and then come to a stop - example when I use the highway and then drive to a town in which I have to stop due to a red light

I have read through this site and have done some work through what I believe it was making this frustrating situation

Replaced faulty TPS
Cleaned IACV
cleaned throttle body
replaced faulty RFPR with OEM fuel regulator

after doing all these steps the car has improve a bit but the issue still remains, wanted to get your inputs here to see what else I need to check to clear this issue. I have been dealing with it for a while now with no solution

please help!!

 

[Jay]

Try donoring a working coolant temp sender (the main green one) and make sure the connector and wiring are in good shape). Seen a few faulty senders giving incorrect signals to the ecu in the past. Symptoms would include low idle and poor hot starting issues.

Jay

 

[Vic-GT]

Hi Jay thanks for your response I have check the coolant temp sensor - the connector was broken so got that fixed but the issue persist so I replaced the sensor and nothing changed

I have cleaned the wax stat of the throttle with carb cleaner and it was all good for about 2 days - I could rev the car and stop and nothing would happen but its back to dropping revs again.

does someone knows what this valve is for? is stick to the right hand side of the fire wall with 2 very long vacuum lines

I removed this valve and recirculated the vacuum lines and the car seems to be idling much better as the revs will stay around 850 when I come to a stop after cruising

 

[Jay]

That looks like the VSV solenoid, stands for vacuum switching valve. Pretty sure it draws air into the charcoal filter for filtering. If it's causing issues you should be able to just blank off the pipes and remove it without too much trouble.

The waxstat under the throttle body is used to inject additional air into the intake during cold cycle. If it breaks down you can get high/weird idle instances.

 

[Rev]

That VSV will also add some revs when the a/c is switched on to help with the additional load.
There is also the air sensor on the driver side at the front of the the air intake to consider
remove the cable and it will default the ecu to 20degC air temp this will add some fuel which can raise the revs if leaning is involved. No easy answer though as the o2 sensor can mess with fueling in closed loop in response to leaning or overfueling.

 

[Vic-GT]

thank you very much for your responses, I have removed the VSV and replaced the IACV as this last was not working at all. I have drive the car for about a week now without any idling issue, I think that my issue was a combination of broken parts that made the car idle so poor.

I will continue to monitor the idling and will keep you posted

regards

 

[Vic-GT]

issue cleared out - I have about 15 days with no idling issues, had the opportunity to fine tune the car yesterday finally after all trouble and I can say its another car now

 

[Jay]

Happy days mate, glad you got sorted.

Jay