Jerking while coasting

Tiny
BLABLABLABLA38
  • 1990 BUICK CENTURY
  • 200 MILES

My car****** while im coasting sometimes when mantaning speed depending on how fast im going (it****** bout every 3 secs.) If I switch to neutral it stops. To me it kinda sounds like its attempting to died. Ive changed the mass air flow sensor. Witch was bad

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Friday, September 30th, 2011 AT 7:34 PM

18 Replies

Tiny
HMAC300
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Check fuel pressure which shold be no lower than 40psi. Clean the throttle plate and iac valve hole with choke cleaner. Do this with engine off. It will start hard after doing this.

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Friday, September 30th, 2011 AT 7:40 PM
Tiny
BLABLABLABLA38
  • MEMBER

So if my fuel pressure is lower than 40 would you stay the best thing to change would be the fuel filter

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Friday, September 30th, 2011 AT 7:45 PM
Tiny
HMAC300
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Actually no the best thing would be to replace the fuel pump and filter. The pump is probably going bad.

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Friday, September 30th, 2011 AT 7:46 PM
Tiny
BLABLABLABLA38
  • MEMBER

Also I belive the hiccups get worse when im low on gas

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Friday, September 30th, 2011 AT 7:47 PM
Tiny
BLABLABLABLA38
  • MEMBER

I got told by one of my friend a mecanic that it might be a motor mount is that a posability

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Friday, September 30th, 2011 AT 8:41 PM
Tiny
JACOBANDNICKOLAS
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Chances are hmac is correct with the fuel pump. A motor mount could cause it, but it's unlikely. You are most likely to feel a clunk when placing it in gear.

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Saturday, October 1st, 2011 AT 1:44 AM
Tiny
BLABLABLABLA38
  • MEMBER

It does it after its already in gear. I beleve it does it with all the gears. Could the oxgen sensor be any problems to this becasue I know thats why my check engin lights on

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Sunday, October 2nd, 2011 AT 12:52 AM
Tiny
JACOBANDNICKOLAS
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It could because it tells the computer how rich or lean to make the fuel mixture. If you have had the computer scanned, let me know the codes you found.

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Sunday, October 2nd, 2011 AT 3:52 AM
Tiny
BLABLABLABLA38
  • MEMBER

Ive had the little key inserted in the computer connector and code 33 shows up its the maf. Ive used a light up tester on the maf connector while the car was on and none of the wires have any juice on them. Would you be able to get me the wireing diagram?

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Saturday, October 8th, 2011 AT 11:38 PM
Tiny
HMAC300
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I've sent two charts, one shows howit's wired and second chart shows how to check it. Chekc your ecm fuse in the fuse box first though as that is where it gets it 's power

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Sunday, October 9th, 2011 AT 12:40 AM
Tiny
BLABLABLABLA38
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I belive you sent me the vacuum hose diagram not the wiring?

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Sunday, October 9th, 2011 AT 3:46 AM
Tiny
HMAC300
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Heres for the maf sensor but still check your ecm fuse that is where it gets its' power and if you aren't getting power check that first

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Sunday, October 9th, 2011 AT 1:05 PM
Tiny
BLABLABLABLA38
  • MEMBER

The red wire was messed up and I fixed it the black wire I believe is grounded good and the yellow wire had no juice on it I tracked it back and it when in to the computer. That ECM fuse is good and had juice on it. I'm not using a volt meter (I don't have one) just using the pokey light tester

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Tuesday, October 11th, 2011 AT 3:53 AM
Tiny
JOHN_T_65202
  • MEMBER

I have the same problem with my 1991 Century. As long as your driving along it is smooth as glass. But when slowing down to a stop the engine starts running rough, sometimes dies. I have had it checked at a dealer service center and an independent and one can figure it out. Heres what I have done so far. Changed ECM, CPS, plugs, wires, coil packs, fuel pump, and MAF. When someone figures this out I'd like to know! I have also unplugged the lock up solenoid to no effect.

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Tuesday, October 11th, 2011 AT 10:20 PM
Tiny
JOHN_T_65202
  • MEMBER

I don't understand it but today I unplugged the MAF and the engine started running smooth. Drove it around a while and no problems dieing out at a stop sign. It looks like I got a defective MAF but it's been too long ago to get it exchanged.

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Wednesday, October 12th, 2011 AT 10:09 PM
Tiny
BLABLABLABLA38
  • MEMBER

Mine doesn't do it when I first start it up but after 1-2 min it starts. I'm almost positive it's the computer. When I bought it the vac hose on the vapor canister was unconnected (not the one going to gas tank but the one going to the engin by the throttle. If I plug it back in it dies when I'm stopped at light, but with it unplugged it doesn't die. The wire comeing from maf to computer has no juice. Would that mean computers bad or could it be something before the computer? Don't want to buy computer just to find out its not the problem.

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Thursday, October 13th, 2011 AT 7:57 PM
Tiny
HMAC300
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It dies because your cannister purge valve is operationg at idle and not supposed to. Replace it and you will probably fix your problem.

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Thursday, October 13th, 2011 AT 8:23 PM
Tiny
BLABLABLABLA38
  • MEMBER

So I replace the ecu for a used one and it completly got rid of the hiccuping. Before I replaced the ecu I was experiencing problems with hesitations when I was taking off from a stop light or sign and also when I got up to like 50 or 55 then came to a stop it would die and I could start it up but when I put it in any gear it would die I'm still having hesitation and stalling when I stop after going fast. I came to realize the problem was the torque clutch converter (tcc). If I unplug the 4 wire cord coming from the tranny it goes away but I still have hessitation. My question is do you think its the converter its self or a sensor? And also where is the converter located in the tranny? Is it between the motor and tranny or by the cover?

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Friday, May 25th, 2012 AT 1:30 AM

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