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bad crank sensor??????????

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QUIP'6'

Brian Roman
Joined
Nov 26, 2003
Messages
4,381
been fighting a bad idle for 4 years and after 2 rebuilds. i have a couple posts saying low o2's at idle. anyway when i first got the car it had .250 play in thrust and it went into the crank sensor. never changed it but it has a slice where the ring dug into it. would this cause an irratic idle even though the gaps are set proper and it starts fine. the problem i am having is when it starts and warms up it starts to idle rough and the 02's are in the 400 to 500 range and it still is cross counting. when i hit the alky test button it jumps to 800 o2's and smooths out till the alky is used up and starts to go back down. this car is perfectly sound with everything new and the scanmaster numbers are perfect 129 blm's and 20 iac readings no exhaust or vacuum leaks and a new gm cam sensor. please help. i have a turbo tweak chip and it should idle locked on in park around 700 to 800. this started out of the blue 3 years ago. when i put it in gear it idles smooth with no misses except i got a surge or hiccup at cruising speed on the highway
 
I think the TT chip goes into open loop idle only when you are in gear. In neutral and park it is in closed loop. Call Eric to verify that. Have you tried another MAF?
 
I think the TT chip goes into open loop idle only when you are in gear. In neutral and park it is in closed loop. Call Eric to verify that. Have you tried another MAF?

it used to run in the 700 to 800 range before and a smooth idle his chips run in open loop in park. as for maf i have an ls1 and tried all settings in translator and a good stock maf ith the same results
 
Clogged injector? Bad injector O ring ? Try removing the injector plugs one-at-a-time while running. TPS/IAC settings.
Man I hate chasing problems. Good luck

Bryan
 
Clogged injector? Bad injector O ring ? Try removing the injector plugs one-at-a-time while running. TPS/IAC settings.
Man I hate chasing problems. Good luck

Bryan
have brand new flowed 50's did this with the 42's and iac and tps are on the money. thanks
 
I think I would still pull the injector plugs to rule out the harness. HTH

Bryan
 
I think I would still pull the injector plugs to rule out the harness. HTH

Bryan
brand new like i said everything is perfect on this car it runs hard and smooth at wot i just have a pain in the a$$ idle. every plug on the harness makes a change when i remove each one. so you are saying that the cranks sensor is good even with the deep gouge in it from the ring digging into it from the thrust going out
 
Odd that it changes if you add alcohol into the equation... what's it do if you change the FP?
 
brand new like i said everything is perfect on this car it runs hard and smooth at wot i just have a pain in the a$$ idle. every plug on the harness makes a change when i remove each one. so you are saying that the cranks sensor is good even with the deep gouge in it from the ring digging into it from the thrust going out

I had one where the bolt that holds it in place backed out a little and the sensor moved into the ring, it got blasted enough to make HORRIBLE noises and still worked, was missing big chunks.

That said - a crank sensor is only $25 or so, I'd throw one on it just in case. I reset the one I mentioned above and drove the car for another week or so before I installed one to replace it. I since gave that old beat up sensor to a friend that needed one, it might still be on his car now. I doubt that is the problem though, I've always seen them either work or not, no crazy business in between.
 
I had one where the bolt that holds it in place backed out a little and the sensor moved into the ring, it got blasted enough to make HORRIBLE noises and still worked, was missing big chunks.

That said - a crank sensor is only $25 or so, I'd throw one on it just in case. I reset the one I mentioned above and drove the car for another week or so before I installed one to replace it. I since gave that old beat up sensor to a friend that needed one, it might still be on his car now. I doubt that is the problem though, I've always seen them either work or not, no crazy business in between.
thanks. as for the fp it just changes my blm's not the o2's
 
wha happened when your crank sensor was bad? didnt yours act up

Yeah it was acting funny. It had rubbed on the 3 rings and got all out of whack. If have had so many issues over the years I cant say for sure what the symptoms were but I am 100% sure that the crank sensor was a problem for one of my miss/hesitation/bad idle problems.
 
Yeah it was acting funny. It had rubbed on the 3 rings and got all out of whack. If have had so many issues over the years I cant say for sure what the symptoms were but I am 100% sure that the crank sensor was a problem for one of my miss/hesitation/bad idle problems.

thanks i guess i will get a new one. whats $40 after spending $20,000 or so on parts
 
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