Need Help - Car Stumbles/Hesitates

U

ULOSE2A6

Member
Joined
May 28, 2001
Hello All,
I am in serious need of some technical help. My 87 GN has developed a serious problem. While driving along it sometimes hesitates or stumbles or buck at low speeds but sometimes it is fine at low speeds. The real problem occurs while driving at around 60 mph or even accelerating to crusing speeds, then it hesitates and stumbles alot more. I have been interchanging parts to see what might have gone bad. I have not had any check engine light come on nor have the scan-master shown any codes or any readings out of alignment other than the speedometer on the car reading alot less than what the scan-master shows while driving along, but the car has had that problem before the hesitation thing came along. Well here is a list of the things that I have tried or checked or changed:
- Fuel Filter changed
- Fuel Pump checked
- Fuel Injectors changed
- Fuel Pressure stays up while hesitation continues
- Assume Fuel Pressure Regulator is fine
- Swapped Computer chip and Computer
- Coil Pack checked and swapped
- New Plugs and Wires
- Checked and swapped cam sensor cap
- Checked Crank Sensor - tight and no apparent damage

Well at first when it started I thought that i got a batch of bad gas or something like that, maybe water in the gas of such, so I drained out the tank and changed the gas and it was still hesitating, it was then that I started swapping parts to see what else could have gone wrong, but till now I cannot figure this one out on my own so I really need help. My computer is down for repairs so I may not answer reply as quickly as I want but I will try my best. I really appreciate any help that you all can offer and I apologize for being so long here. Thanks again.
 
I know this isn't the most definitive answer you've ever heard, but here goes.

My GN was doing something very similar to yours when I first bought it. It would buck and cutout whenever it wanted, whether I was cruising at 30 or 75. I tracked and tried everything and the only thing that seemed like it worked was installing the ground relocator kit from Casper's Electronics.

Now, I'm not telling you to run right out and buy the kit and install it by any means. I don't even know if your car has one or not. I'm just saying that after I put this kit on my GN, the bucking and jerking stopped all together. It was very frustrating until the day it all went away, then I was a happy camper again. :D
 
Thanks alot Tom, it is worth a try for sure. At this point I am willing to try anything. I will try to check the grounds behind the heads and make sure that they are tight in the meantime. Thanks again.
 
Just another couple of things to check I guess: MAF, Module. Probably not a vaccum leak, but check that too. Good luck.
 
Mark,
I forgot to say that I had swapped out the MAF and I had checked and swapped out the coil pack and module as well. I will definitely check for vacuum leaks and I will let you know what I find. Thanks alot for the suggestions and keep them coming guys, every suggestion helps no mattter how insignificant you might think it to be. I keep thinking that I forgot or overlooked something simple. Oh well we'll see how it goes.
 
I had an experience similar to Toms'. It also showed up on my Directscan when all values would suddenly drop to "0" for a few frames and the it would kick back in again. the grounds at the back of the passenger side head were all gunked up & greasy, and apparently not making a good connection. re-doing those grounds did the trick.
 
Ulose2a6-> where are you from in Florida? I just recently am experienceing the same thing. My car after driving for a while on and off boost will suddenly buck and hesitate. You can not hear it from the motor, but feal the car pull back for a second like a hiccup. Is this the same thing you are experiencing or is the hesitation longer. Also, my car is stalling intermittently. This happens only on deceleration.
 
Wicked6, it sounds like your problem is with the TCC solenoid in the trans. For a car to stall during deceleration means the solenoid is malfunctioning and locking the torque converter which bogs the motor and kills it.
 
Tom-> I have a NLU TCC. I am pretty sure it is in the chip. I am currently in the process of fixing that. Just need to change three areas in the chips memory!

The stumble is new though.
 
The hesitation does seem like a hiccup and to me I thought it to be more of like the car was not getting enough fuel, but the hiccups do not really occur when the car is decelerating, it does it constantly while trying to get up to crusing speed of about 60-65mph or so and I think it does it more throughout the acceleration range when the car heats up. I got a message from a friend of mine to check the steel cup inside of the cam sensor and see if that is loose. I will have time tomorrow to check out all these leads and I will definitely let you all know what I come up with. Thanks again for all the very helpful suggestions.
 
Originally posted by wicked6
Tom-> I have a NLU TCC. I am pretty sure it is in the chip. I am currently in the process of fixing that. Just need to change three areas in the chips memory!

The stumble is new though.
Click to expand...

What have you changed recently, is the chip new, or different than before the stumble occurred? Does your Direct scan show anything related to when the stumble happens? Are you changing things in the chip with a Tuner software or how will you change the areas you mentioned in the chip ?
 
A friend of mine has a tuner software to make the chips. The stalling started to occur after I put in this new chip.

As far as the car jerking that happens when I am cruising. This started to happen after I took the IC off and tightened a loose bolt and put it back on.
 
First I would try a known good chip that works well in someone elses car. If that makes no difference, then you will know that it is probably not the fault of the chip. Not to be belittling your friend's tuner software, but does he really know what he is doing with it? Again I dont mean to sound arrogant but there is more to chip programming than just buying the software, a burner and changing stuff around in it. Some chips, (Thrasher for instance) are tamper proof, and will not respond to changes with software tuning the way you think they will. Copying some guys brand * chip then changing it to your injector size does not mean that you now have a brand * chip burnt for your inj size. There is a lot more to it than that . Removing and replacing the IC should have no affect providing the hoses aren't leaking and all clamps are tight. What chips have you run in the car before you used the one you have now? From the looks of your signature, you are capable of mid 11s with that combo. So something is definetly amiss if your best et so far has been mid 12s.

I would try to narrow it down to whether it is a programming problem, or a problem with the car first, then go from there. Also, if you record DS files while it does this that may give you an indication of what is going on.

Good luck
 
The only other chip I have is from PTE. I will try that and see. It was made though for a stock TC.
 
I too have tried swapping out the chips and I even swapped out the computer, but the hesitation continues. I have noticed that after swapping out the 009's with bluetops that the hesitation seemed worse, making me suspect that the problem is fuel delivery. The trick here though is that the fuel pressure is constant while the hiccups are happening. The other thing is that the BL's are around 90 while idling and I do not have a number for while driving as yet since I have been borrowing a scanmaster to check things out. But I will see what the BL's are while the hiccups or hesitation are happening. I am not too familiar with how the BL's are to be interpreted but I am inclined to suspect that I am not getting enout fuel when I need it and that is the cause of the hiccups or hesitation. Oh well the problem continues.
 
Double check your fuel pressure at speed. I had a similar problem and it ended up that I had pinched the hotwire to the fuel pump. At idle it was fine, but when the car would move, the body would come down on the wire and pinch it.
 
Brad, I did check the fuel pressure and it was steady when the hiccups occured and I also checked to see that the fuel pressure increased with boost and so I concluded that the fuel pressure regulator and the fuel pump was both fine. This weekend I also checked that the steel cup inside the cam sensor was not loose and also swapped the map sensors and other sensors on the passenger side rail, but the hiccups/hesitation continue.
 
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