Fixed --95 Monte Z34 Missing/Erratic Idle Bucking/Shuddering

[jb88ci]

Was a bad plug wire on #5. The terminal had come of the wire under the boot. Cold, she ran fine, warmed up ran like crap. The miss was being compensated for by the computer, i guess, causing the erratic idle as well as teh miss.


Hey All...i think i love this site.

Last month I bought the describe car...i love it. About a week ago i started having some issues.

At idle it misses or is erratic but isn't throwing the idiot light. It's suffering poor acceleration below 2000 rpm and is Bucking/Shuddering if you try to acclerate slowly out of a cruise condition after the tranny has kicked down to OD.

New air filter, PCV valve, known good EGR valve, fuel filter. The wires don't throw sparks in teh dark. Don't know when plugs were changed. Gonna do it this weekend.

Erratic idle goes away when IAC unplugged but it think that's driven by TPS signal. Also, engine runs cool unless idling for prolonged times, then guage comes up to about half indication and fan kicks on.

No smells and economy is as good as it was when i drove it home. No known performance mods, engine has 130,000 km on it and car is a cream puff, was well taken care of.

Any ideas? I'm thinking TPS...can't read codes as its a OBDI plug with no wire in the B slot.

Also, what can i rig to read the codes. Have laptop, will travel.

thanks....

[z34phoenix]

RE: 95 Monte Z34 Missing/Erratic Idle and Bucking/Shuddering

well for starters, you have a OBD 1.5
when you go to change the plugs, i would recomend doing the full set of intake manifold gaskets Upper and lower. gaskets are a commen problem with these engines. as for the temp at idle. that is normal.
also tps's are commen problems too.

IIRC the problems you are discribing i had when i had problems with TPS sensor. but if your going to do the plugs do the gaskets, cause they will be needed soon anyway

[SappySE107]

RE: 95 Monte Z34 Missing/Erratic Idle and Bucking/Shuddering

Where are you located? Someone may be local to you that can read codes. With a multimeter, you can tap into the TPS wiring and see if the voltage moves in a smooth and linear fasion as you adjust throttle. Scan tool would tell you as well without touching the wiring.

Could be a bad coolant temp sensor but I haven't had one go bad, so I only know how others have desribed their car when that goes bad as well.

Check your plugs and see if 1 or 2 are looking different than the rest. At least pull the front 3 and check those out since each of those is on a different coil pack.

How old is your O2 sensor?

[jb88ci]

I'm in Winnipeg

I'm in Winnipeg, if anyone happens to have a compatable scanner. I wouldn't object to putting out some cash to purchase cabling/software to hook my laptop up, if you can send me in the right direction.

I've got the o-ring leak as well, not too bad yet, but definately wet. I'm going to pull the intakes etc off over christmas break and seal that bitch up...maybe i'll mig weld it. Just kidding...

Think i'll change the TPS an spec when I've got hte throttle body and intakes off. It's a 95 so the throttle body is at one with the plenum. Stupid design.

I'm gonna peruse the site to look for some low buck performance upgrades as well.

thanks for the replies.

[SappySE107]

RE: I

the only program I am aware of costs 180 bucks. efi-live. Then you would need the $80 cable setup from moates.net to connect the laptop to the car.

How low buck are you looking for performance? The cam timing is probably the best bet if you can do it yourself. I have a chip that isn't dyno tested yet but has had good results so far with the 94-95 computer. I have a chip for the 6/6 timing or stock timing, both with the maf screen removed. FFP has an underdrive pulley that will help out as well and isn't a lot of money. fastfwdperformance.com

[jb88ci]

Well, I'm an aircraft mechanic by trade and a certified Turbine Engine Overhaul Technician to boot, so I guess I'm handy with a wrench. I currently teach at a community college in Winnipeg.

Low buck as in not rebuilding the motor or having the car down for more than a couple days at a time. It's my daily driver and my wife doesn't like to be inconvenienced by me taking her Jeep to work.

Chips are good, exhaust manifold, cat backs, timing changes etc. I can follow technical instructions without too much trouble.

[SappySE107]

Getting a 2.5" mandrel bent cat back put on with a better Y pipe transition (if you want to keep the dual exhaust), and some better mufflers. For mufflers, go for sound really, as all the 2.5" mufflers doubled up will support more flow than the motor is gonna put out.