need help....rough idle when cold???
Thread Starter
Drifting
Joined: Oct 2003
Posts: 1,594
Likes: 0
From: CALGARY ab
need help....rough idle when cold???
having rebuilt L98 '89 picture on left,
what was done? port&polished heads, new springs, new cam , 1.6 RR's, flat top 5cc, bored out 48 to 52mm. ( machined bore and bearing shaft, work done here in garage), new injectors, new ecm, new air sensor, removed all egr and emissions. set Iac-450rpm/tps .54v..datamaster tune was used.. everything including air/fuel ratio is within perimeters, open/closed loops are normal
the problem is when first start, it idles rough for about a minute, then smooths out.. what do ya think might be wrong?
any suggestions?
what was done? port&polished heads, new springs, new cam , 1.6 RR's, flat top 5cc, bored out 48 to 52mm. ( machined bore and bearing shaft, work done here in garage), new injectors, new ecm, new air sensor, removed all egr and emissions. set Iac-450rpm/tps .54v..datamaster tune was used.. everything including air/fuel ratio is within perimeters, open/closed loops are normal
the problem is when first start, it idles rough for about a minute, then smooths out.. what do ya think might be wrong?
any suggestions?
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
You list a new air sensor, but did you also replace the CTS? What temp is it indicating on your datamaster with a cold motor? Should be real close to the MAT. Since the CTS takes the place of the choke, it can make it run rough if there's too little fuel.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Probably should have added that you can monitor the BLM too. See what it is the minute it goes closed loop. If lean, suspect the CTS circuit, restricted injector (though they're new so that's a low probability), or the added air flow doesn't have enough pulse width from the stock chip for cold operation at which point you're going to have tweak it a bit.
Thread Starter
Drifting
Joined: Oct 2003
Posts: 1,594
Likes: 0
From: CALGARY ab
Originally Posted by SunCr
Probably should have added that you can monitor the BLM too. See what it is the minute it goes closed loop. If lean, suspect the CTS circuit, restricted injector (though they're new so that's a low probability), or the added air flow doesn't have enough pulse width from the stock chip for cold operation at which point you're going to have tweak it a bit.
problem is EST module.. replaced .. reset iac / tps volt good @ .543...slightly high idle..700 park..
REpaired .. thank you
