Hesitation:
Thread Starter
Instructor
Joined: Jul 2009
Posts: 201
Likes: 0
From: Orland Hills ILLINOIS
Hesitation:
Hey guys glad to be back. Been working on my 84 crossifre here. I have finished a complete tuneup with new wires plugs etc, changed fuel filter etc. I now have a much better running car. It still has a hesitation though when you decelerate and then accelerate again when going between 25 to 30 mph. I replaced the fuel pump also and noticed a considerable difference. Car runs great now but when your driving and take foot off gas and it goes down between 25 and 30 mpg when you step on gas it hesitates and you can feel it like it wants to die. But if you push your foot down on accelarator it takes off. I cannot figure this out. It has done this since I bought it. I thought after the tune up, fuel filter and pump this would solve the problem.
Was going to do the work reguardless because it needed it.
Just wondering if anyone has any idea what this could be?
Any help would be great. And I thought you guys would know in anyone would, thats for sure
Thx
Kevin
Was going to do the work reguardless because it needed it.
Just wondering if anyone has any idea what this could be?
Any help would be great. And I thought you guys would know in anyone would, thats for sure
Thx
Kevin
Racer
Joined: Sep 2004
Posts: 258
Likes: 0
From: Coram NY
I would look for the easiesty and cheapest things first.
did you check for error codes?
did you check your base tiiming?
did you set thre IAC and set the throttle sensor?
next, at idle take throttle body cleaner or starting fluid and spray it around the engine (near any vacuum line & by the PCV lines, if the engine rpm picks up, good sign of a leak.
does the hesitation happen in open loop? or it does it all the time.
It could be your MAF, I dont know if you can disconnect your MAF and run without it to test for the hesitation.
Tom
did you check for error codes?
did you check your base tiiming?
did you set thre IAC and set the throttle sensor?
next, at idle take throttle body cleaner or starting fluid and spray it around the engine (near any vacuum line & by the PCV lines, if the engine rpm picks up, good sign of a leak.
does the hesitation happen in open loop? or it does it all the time.
It could be your MAF, I dont know if you can disconnect your MAF and run without it to test for the hesitation.
Tom
Thread Starter
Instructor
Joined: Jul 2009
Posts: 201
Likes: 0
From: Orland Hills ILLINOIS
Hesitation
Yep, checked all those things. No error codes at all. I have no MAF. Its a 84 crossfire. They used the speed density on this not MAF.
Car runs great except for that. I will get some cleaner and try that but not sure if maybe the injectors just need to be cleaned or replaced?
Car has 93000 miles on it and the injectors are original I am sure.
I am just replacing stuff I know has not been done on the car at all. Original owner took good care of it but he did not want to put any money into it at the end.
Thxs for the info but info but if anyone else has any ideas let me know.
Kevin
Car runs great except for that. I will get some cleaner and try that but not sure if maybe the injectors just need to be cleaned or replaced?
Car has 93000 miles on it and the injectors are original I am sure.
I am just replacing stuff I know has not been done on the car at all. Original owner took good care of it but he did not want to put any money into it at the end.
Thxs for the info but info but if anyone else has any ideas let me know.
Kevin
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 207
From: Orlando FL
That problem sounds like symptoms from a TPS. I would manually measure the wiper voltage out with a DVM.
Just tap into the wire and see if the voltage goes up steady as the throttle is slowly opened. This can be done with ignition on but engine not running.
See if you find a flat spot of fall off in the voltage as its opening.
Just tap into the wire and see if the voltage goes up steady as the throttle is slowly opened. This can be done with ignition on but engine not running.
See if you find a flat spot of fall off in the voltage as its opening.
Racer
Joined: Sep 2004
Posts: 258
Likes: 0
From: Coram NY
That problem sounds like symptoms from a TPS. I would manually measure the wiper voltage out with a DVM.
Just tap into the wire and see if the voltage goes up steady as the throttle is slowly opened. This can be done with ignition on but engine not running.
See if you find a flat spot of fall off in the voltage as its opening.
Just tap into the wire and see if the voltage goes up steady as the throttle is slowly opened. This can be done with ignition on but engine not running.
See if you find a flat spot of fall off in the voltage as its opening.
Tom
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 207
From: Orlando FL
Actually it is best thing to do is both tests. The resistance check is good also and should work to show up a problem. Only a very small current from the meter is across the TPS.
But you may possible get a different result when looking at the voltage off the wiper. When its connected, there is a normal current thru, and a load on the TPS. The voltage out is what the ECM is actually seeing and is a truer more actual test of operating conditions.
But you may possible get a different result when looking at the voltage off the wiper. When its connected, there is a normal current thru, and a load on the TPS. The voltage out is what the ECM is actually seeing and is a truer more actual test of operating conditions.
