idle surging

J_lope82

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So I just rebuilt the engine and installed bigger cams and I know I need a tune. But I’m breaking in the engine before I take it to get a dyno tune. Meanwhile the thing doesn’t want to idle. Is there anything I can do to help it idle better until I get it tuned?
 

lwarrior1016

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Air to fuel ratio is going to be wrong due to the increased airflow from the cam. The computer will compensate to a certain limit, but it won’t run correctly.

If you’re planning on a dyno tune, take it asap. Breaking them in on a dyno is better than putt-putting. The rings need to see cylinder pressure and load on the engine to bed in correctly.
 
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ttocs

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you might be able to talk to your tuner to get a conservative tune to get it to the shop if they are cool and you prepay but as he said if the tune isn't right it can cause problems.
 
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J_lope82

J_lope82

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You know I had it never thought about it that way. I’ll stop driving it and ask a tuner about that. Thanks
 

Joeminnesota

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So I just rebuilt the engine and installed bigger cams and I know I need a tune. But I’m breaking in the engine before I take it to get a dyno tune. Meanwhile the thing doesn’t want to idle. Is there anything I can do to help it idle better until I get it tuned?
Idle issue is common w/new cams and no tune. I had to do the same thing - break in time to seat the new clutch and to make sure cooling is working, no leaks, etc. You can crack the nut loose on the idle screw loose and turn it in a bit to try and get an idle, and will need to milk the idle when you come up to stops when the engine is warm. I broke mine in 350-400 miles before going to dyno - it may be lean in spots or rich in spots, so just don’t beat the daylights out of it, and know that it will probably run tougher and sputter during tip-in (partial throttle) and may load up when idling. It may pop at lower rpm under load, so keep the motor at moderate rpm’s when cruising, so it isn’t lugging. Not fun in any traffic so best in rural areas with some stops & goes. Much easier with a clutch car.

Sometimes you have to run the motor in before the dyno, but it won’t be running its best. In my case I cannot strap it on a dyno with a brand new clutch kit & flywheel - they need some break-in. They are correct, though, that fuel and timing will be off quite a bit with cams. If you change up your injectors, a base tune is definitely needed so you don’t wash out cylinders.

When you go in for tuning, change oil and let them know you adjusted the idle (mine was all the way in w/stage 2 cams and still only idled well after cold start-up .. once warm idled like garbage). The tuner can adjust everything for drivability and tip-in.
 
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NicksGTR

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Get a SCT X3 if you don't have one and download a file from a tuner such as Lasota Racing, Delaware, Oh. Did you change injectors? You're going to have to down load a start up tune to get to run well on the dyno.
On the SCT X3, this model was designed for the early years of OBD II and a lot is eliminated in the later X4 model.
 
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J_lope82

J_lope82

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So when I bought the car it already had 24lb injectors. It also had a custom tune. The thing is I can’t just get a tune around here. There aren’t any reputable tuners that I know of. They are all at least a couple of hours away. I have asked a few and they all said they won’t tune cars my year and with stock ECM. Still looking.
 

lwarrior1016

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Yeah, that’s going to be a problem that you’ll run in to. The moates chips they used to use aren’t really available anymore, and the computer is too old to use hptuners.

You may be able to get the sct and find someone to remote tune it.
 

Joeminnesota

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If it has 24’s you definitely need a tune from someone. Sounds like you already have a basic custom tune. To add to my original response, you don’t want to change that screw on the TB very far - the ECU works in conjunction w/the IAC to determine your idle. Evidently you can unplug the IAC temporarily, start the car and adjust the screw slightly until it idles around 600rpm or so, then plug IAC back in. The screw is “calibrated” at the factory at a specific blade opening and too much gap will mess with the ECU’s ability to compensate and also may mess with how the TPS responds. In the end it needs a tune to idle and tip in - especially with the larger injectors. You probably just need something better than is in there now.
 
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J_lope82

J_lope82

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So I’m confident that with some refreshing of my memory I can do my own tunning. I know all the parts of the car and what they do. I’m familiar with the sensors, their signals and air fuel ratio, PWM, data logging etc. etc. I can distinguish pinging(detonation) when I hear it, so on and so forth.

What tools do you all recommend I buy to do my own tunning??
 
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J_lope82

J_lope82

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If it has 24’s you definitely need a tune from someone. To add to my original response, you don’t want to change that screw on the TB very far - the ECU works in conjunction w/the IAC to determine your idle. Evidently you can unplug the IAC temporarily, start the car and adjust the screw slightly until it idles around 600rpm or so, then plug IAC back in. The screw is “calibrated” at the factory at a specific blade opening and too much gap will mess with the ECU’s ability to compensate and also may mess with how the TPS responds. In the end it needs a tune to idle and tip in - especially with larger injectors. If it is on stock tune and now 24lb injectors I would not run it without a tune to compensate. The injectors may be too rich and can wash out the cylinders.
I had already tried to use the throttle screw it just idled too high. If I back the screw out it tends to die. I’ll try it again using that process you explained.
 

ttocs

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do you have an afr gauge? They are helpful for remote tuning with the stock ecu. If you go with another ecu then it will come with one type or another.
 

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