Idle Surge. Been through it all.

[Silverspyder]

I've got this nagging idle surge problem since my rebuild. Before you ask, yes I've been through the troubleshooting guide.

It ONLY surges WHEN MOVING when the engine isn't fully warmed up. I cold start the car and it idles fine. As soon as the wheels start rolling it begins surging between 1-2k rpm. As soon as I stop again it settles right down to 850rpm. I'll be driving and while rolling up to a stop sign or stop light, push in the clutch...surges. Again, UNTIL I STOP. When the car is fully warmed up, it idles just fine all the time.

Brand new oem ISC, FIAV blocked off, EGR blocked off, no boost leaks not even from the injectors or TB. Car has been dyno tuned.

Any other ideas? Is there a sensor I'm forgetting about that controls idle only when at speed that could be bad?

 

[sjrdsm]

cam or crank sensor mine did the same thing it was the crank sensor

 

[dsmcurse]

My car sorta does that too a bit like you explained. But you know what? Even though you push in the clutch or go to nuetral and you coasting, the engine still has a slight amount of load. Basically if coasting in nuetral with engine running there will still be a VERY slight amount of load on engine untill car comes to a complet stop. Even though its in "nuetral" the moving tires are still moving the axles and there is still oil splashing around a bit in tranny and some how the crankshaft can just tell that the tranny still has some action goin on.


On my car when I clutch and half shift just to neutral and come coasting into the parking lot or up to the stop sign my idel is like 1800 while I'm rollin. But once I stop completley it settles down to almost exactly what my target rpm was for idle. I aim for 900 but if she's around 50-100 rpm away from that I'm good.

I think what your experiencing is sortta normal. It sounds like you got all your bases covered as far as what to check. Only thing I can think to remind you is to double check your base timing at idle and make sure that too is all good. That can play a role in your idle settings.

 

[Silverspyder]

If it just held a certain rpm while I was costing I could deal with that, but it'll bounce from 1k-2k-1k-2k-1k...does it fairly quickly until I stop, then it just drops down to idle speed.

cam or crank sensor mine did the same thing it was the crank sensor

The car shouldn't even run with a bad crank sensor if I'm not mistaken.

 

[dsmcurse]

If cam angle sensor to advanced and bass idle set screw to far turned out, in certain situations the idle trys to take over and then the timing portion of it tries to make a correction and you end up with these to guys kinda fightin each other more or less.


I've dealt with idle surge and was totally pist off because I had no leaks and new parts and blah blah blah and what my fix ended up being was I had cam angle sensor a bit to much advanced and BIS screw out to much.

I loosened cam sensor and just a tiny scotch bumped it toward radiator. Just a bit was all it needed. Tighened in screw a bit and she purrs like a kitten now. Make sure your bass idle timing is not to much advance

 

[arabeclipse]

Check your TPS because that can cause surge. I had the same issue. Replaced TPS with one at a junkyard and it cured it.. until it went bad again . So best off checking and if it's bad, probably best to get a new one.

 

[Silverspyder]

If cam angle sensor to advanced and bass idle set screw to far turned out, in certain situations the idle trys to take over and then the timing portion of it tries to make a correction and you end up with these to guys kinda fightin each other more or less.


I've dealt with idle surge and was totally pist off because I had no leaks and new parts and blah blah blah and what my fix ended up being was I had cam angle sensor a bit to much advanced and BIS screw out to much.

I loosened cam sensor and just a tiny scotch bumped it toward radiator. Just a bit was all it needed. Tighened in screw a bit and she purrs like a kitten now. Make sure your bass idle timing is not to much advance

Good stuff, I'll have to check. The BISS def isn't out very far...2 1/2 turns from the bottom, have set the idle properly multiple times by grounding the jumpers so that isn't an issue.

 

[sjrdsm]

yes it will run if it is the crank senor is bad it will run good cold intel it warms up all the way then the ecu will try to get a signal an it wont so it will give the car more gas an take it away (surge)
cam senor keeps the cams in time an the crank senor will keep crankshaft in time an the timein has to be on point if any of them senors fail will make the car surge when it is warm

 

[dsmcurse]

That's incorrect, 1st gens ONLY have a cam angle sensor. And cam or crank sensor aside, all it is, is cylinder position sensor. Weather its mounted to the cam or the crank all its doing is reporting the same info (cylinder position referance)

To say a cam sensor keeps the cams in time and a crank sensor keeps the crank in time is a totall misinturpritation of how things REALLY work. That's complete bunk and wouldn't want people who are actually resourcing a problem to read that and misinturpret it as how things actually work.

 

[Silverspyder]

yes it will run if it is the crank senor is bad it will run good cold intel it warms up all the way then the ecu will try to get a signal an it wont so it will give the car more gas an take it away (surge)
cam senor keeps the cams in time an the crank senor will keep crankshaft in time an the timein has to be on point if any of them senors fail will make the car surge when it is warm

Car DOESN'T surge when it's warm. Only when cold.

 

[dsmcurse]

Well please tells us when you find a CRANK sensor on a 1G...

 

[Silverspyder]

Now we've upgraded to only until it's warm, to pretty much all the time. Over the weekend and today, it's doing it even when fully hot after driving for 30min. Driving me nuts!

 

[Cdc1221]

Fat chance but could it be the brake booster hose leaking at the booster

 

[miguelmcv]

I used to have surge on both of my 2gs, both where having the same idle problem as yours, But one was always like that even on cold, it end up being a huge exhaust leak, I fixed it and made some adjustments to the throttle cable and biss and it fixed the problem.

My other car which was doing the same thing, But this was doing it only when Hot, It never surge when first start, I can leave the car running all day 8 hours and it wont surge unless I move it, if I drive it, on the first stop it will start surging and will never stop till I turn it off and let it cool down, I new it was the ECU, Because I swap to an Eprom, I swap the ecu back and came back to normal.

I send the ECU to ECMTuning to check and they fixed it,.. At first, they email me saying they didn't find anything and was claiming that 90% of the problems were from the car it self and not from ECU, I told them that it takes a wile to surge so they test it again for longer time and I received another Email later on saying they found the problem..

It seems like 1gs and 2gs are very alike on the ECU, so I would look into that.