Odd problem

[Fiddledeede2]

I have a 1994 ATX with about 90K miles. In the last few months I have been having the following problem. Intermittently, when I take off from a stop, the car moves then a second or two later, it starts stuttering 4 or 5 times and then takes off just fine. By stuttering I mean that it stops then goes then stops then goes at a rapid rate for another two or three seconds. It is worse when I take off on an uphill and when I take off fast (like when crossing traffic). It doesn't always happen and I can make it not happen by taking off very, very, very, very gently.

I checked the codes and the only one I have is a stored 124 (Throttle position voltage was higher than expected) on the Engine off test. The check engine light comes on occasionally while I am driving but does not stay on. Also, occasionally while the car is running it will hesitate or surge which may account for the 124 stored code..

Anyone have any idea of what is going on. Help!!!

 

[SHeepsclOthing]

Im almost certain its a fuel related problem. Sounds like its being starved. How old is your fuel filter, does your pump whine louder than usual, try checking fuel pressure. Code 124 shouldnt be causing the problem. If its reading a voltage too high, its thinking its get more throttle than it actually is which would result in a slightly richer mixture. So I doubt thats your problem. It could be setting off the CEL though. Take a listen at the fuel pump and replace that filter.

 

[Fiddledeede2]

Thanks ! Hopefully it is the Fuel Filter (cheap fix). It was probably 2 years ago that I got a new fuel filter but I bought it at Wal-mart so perhaps it was lousy.

I'll get a new one and try it this week.

 

[SHeepsclOthing]

If the filter is the problem in this case, it might not be the filters fault. When MTBE was taken out out gasoline supply, they replaced with it an alcohol, which will clean everything, making the filter work harder. Im not saying its the reason, but a possibility.

 

[Redskull]

try cleaning the MAF. too much air = not enough gas

 

[Fiddledeede2]

Thanks! Do I just remove the MAF and clean it with carb cleaner?

 

[betterman]

yeah take it out and use some type of electrical friendly cleaner. Be very careful not to wreck those thin filaments though. Cleaning the maf can make a huge difference to the performance of this engine.

 

[THE Shobra]

yep same prob on mine but only when the car is cold. Let us know what you find out.

94 mtx

 

[shofan33]

You might want to check that TPS too because in an ATX that's what controls the upshift. And if it's getting funky reading when your on the throttle it can have the same effect.

 

[Fiddledeede2]

Thanks Shofan33. How do I go about checking the TPS?

 

[morpho18]

are your battery cables firmly connected? my car was doing this when my negative battery cable was disconnected.

 

[k_mesaros]

Have you serviced your transmission ever? Torque converter shudder can feel like a misfire or fuel delivery issue.

Kevin

 

[SHOtimer]

You are getting a code for the TPS, replace it.

Also, how are your plug wells? Full of oil?

Doug

 

[shofan33]

There's three wires, one is ground one is 5 volts ref. all the time and one is signal i dunno which ones which.
But if you take a voltmeterand snap the throttle the one that moves is the signal.
Then when you found the signal ou want to move it real slow to WOT and check for any flucuations.

 

[Fiddledeede2]

Thanks for all the suggestions.

My car wouldn't start outside the grocery store yesterday so I had it towed to the shop. I need a new starter.

Here's some wishful thinking - the starter was responsible for the stuttering

 

[Fiddledeede2]

I am reminded once again why I HATE taking my car to the shop. As I am driving home after picking it up I realize that the Air Cond is not working. I call them and say I'll stop by tomorrow. They look at it and say "can't be us - the AC and starter are on opposite sides". I just looked at the guy and said "When I brought it in it worked and when I picked it up it didn't - so what are you going to do about it". After about 15 mins they found that a cycler or something had been bypassed. RRRrrrrr!!!!!!!

 

[Fiddledeede2]

Just a quick update.

I cleaned the MAF and that helped considerably but it still stuttered at times although considerably less often. I then replaced the air filter and that helped even more. At this stage, I would say it is about 95% fixed. It still stutters when I take off from a stop on sharp uphills but that is the only time it does it. Anyone have any ideas why it may occur in that situation.

Thanks