RD1970

I just finished a complet rebuild on my trucks engine 22re all engine builder stuff. Now when I pull up to a stop the idle will fluxuate between 1000-2200rpm and sometimes stick at about 2500rpm. Has anyone had this happen before? I'm not sure what is going on, the engine has been modified over
bored, larger valves,port work on the head and larger cam, could this be
causing the computor to have problems ?

gametom

do you have your idle set to 700-800rpm's? the fluctuation in the idle is generally that the idle is set to high.

RD1970

Idle has been set at around 900 rpm. To add to it the fluxuation only seems
to happen after i have been driving for awhile and come to a stop. if you start it up cold it acts fine.

TNRabbit

Is it an auto or manual tranny?

RD1970

5-spd Manual

TNRabbit

Is your Throttle Body butterfly valve closing all the way when the engine is warm? Sounds like it's sticking...

RD1970

throttle body is closing all the way I'm pretty sure the problem is in the electronics by the way it acts

DaveInDenver

Mine has similar issues. Also just got done rebuilding the engine, used a Engnbldr 261C cam. Mine is actually getting better as I troubleshoot and debug problems. One thing that was causing part of my problems was apparently an air bubble in my cooling. I burped the cooling and drove around with the heat cranked up (the vent on recycle for sure!) for a while and the idle has settled down somewhat and the level of coolant in the recovery bottled changed (I check it in the morning before leaving for work, same time, same conditions each time). My cold idle is OK other than during the warming up period I'll get that high idle kick with the brake pedal depressed. That is because my idle is set higher, about 1000 RPM, as I fiddle with getting the idle to smooth out a bit. My troubleshooting indicates that my EFI temp sender (called the ECT in the book) is failing. Not completely failed, but I check the resistance when I get home from work and with the engine well warmed up and evenly hot, the resistance the sensor reports will vary slightly. So I'm planning on replacing it. My TPS was out of adjustment, that helped at least make the problems more repeatable, even if setting it right didn't solve the problems really too much. Check the AFM, although there's really nothing to calibrate normally (you can dial the AFM to change the mixture). Finally, make sure all the vacuum hoses are right and not leaking. I'm going through and replacing all my vacuum hose as a just in case. The main problem I have is after sitting at a stop light for maybe 15 second, the idle gets rough. Slowing down and the initial return to idle are all pretty smooth, but sitting for some time the ECU seems to decide something needs to change and the idle gets rough. Either a sensor is giving out of range readings or a VSV or something is kicking it. I'm also wondering if the O2 sensor is out of range. I have no codes stored, so whatever it is has not completely failed. Some of this might just be the characteristic of a more aggressive cam, but the way the idle suddenly gets rougher and occasionally it'll be hard to start has me convinced that once I figure it out, the cam shouldn't make the idle all that rough. In my case I'm fairly certain it's not spark, I have new cap, rotor, plugs, coil. The wires are only 2 years old. I had the injectors cleaned, so they should all be firing evenly. My cold start injector was also cleaned, but it's possible that if the ECT is out of range that the ECU is pulsing the cold start thinking the engine is cooler than it really is. Doubtful, but possible. The only thing I have not really been able to test is the aux idle thing under the throttle body. That is an $100 part that I hate to replace without knowing how to test it. The only thing I've been able to think of is to pinch the little coolant lines to it and see if it goes away and that has not worked yet. Now that it's warm consistently here, I'm probably going to clamp those off permanently and see what happens. It's been in the 60s in the morning and so I don't think the engine will miss being 'choked' (it works like a choke on a carb) in the mornings.