94 missing, stutters when hot
Thread Starter
Intermediate
Joined: Mar 2004
Posts: 35
Likes: 0
From: Overland Park KS
94 missing, stutters when hot
Shes been doin it for a while and from looking on the forum i get the impression that it is an opti problem.... the missing will kick in either in 2nd and 3rd with a little more than half full throtle and at high rpms...it will also kick in 5th and 6th goin about 45 to 55 with more than half throttle and at low rpms.... is there anything else that i should check before droppin some cash on an opti, or do you think it is a pretty safe bet that the opti is the cause of the problem? If opti should i stick with a 94 or get a 95 96 opti
Only mods-- Vortex cold air intake, diff MAF, Hypertech chip, no cats
Only mods-- Vortex cold air intake, diff MAF, Hypertech chip, no cats
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Re: 94 missing, stutters when hot (johnandblairspolovet)
Welcome! :seeya
A few questions, and some things to look at:
1) How many miles?
2) Is it the original opti?
Suggestions:
1) Check the coil and coil wire. The coil wire is prone to wear from rubbing against metal parts...
2) 95 and 96 opti's won't fit prior years without lots of changes - timing gears & cover.
3) heat related... I am thinking fuel pump. or relay. but I doubt the relay, cause it is backed up by the oil pressure switch.
4) conventional tune up. if you are still running the original AC Delco Platinum's, they are more than likely toast. They have a tendency to lose their platinum pucks after a while, causing some serious gap issues - from .050 to .065. check the wires, too.
5) there are several options available now for opti replacements. DynaSpark, which updates the existing design and, LTCC and DelTeq (I think thats the name) with replace the highvoltage side with different coil pack options.
keep us posted!
A few questions, and some things to look at:
1) How many miles?
2) Is it the original opti?
Suggestions:
1) Check the coil and coil wire. The coil wire is prone to wear from rubbing against metal parts...
2) 95 and 96 opti's won't fit prior years without lots of changes - timing gears & cover.
3) heat related... I am thinking fuel pump. or relay. but I doubt the relay, cause it is backed up by the oil pressure switch.
4) conventional tune up. if you are still running the original AC Delco Platinum's, they are more than likely toast. They have a tendency to lose their platinum pucks after a while, causing some serious gap issues - from .050 to .065. check the wires, too.
5) there are several options available now for opti replacements. DynaSpark, which updates the existing design and, LTCC and DelTeq (I think thats the name) with replace the highvoltage side with different coil pack options.
keep us posted!
Thread Starter
Intermediate
Joined: Mar 2004
Posts: 35
Likes: 0
From: Overland Park KS
Re: 94 missing, stutters when hot (bogus)
Its got 103,000 miles on it and ive had it since 70,000 so im not sure if the guy that had it before me changed the opti..... Yea it only misses when its hot and has been driven for 20 to 30 minutes... when i first take it out and get the temp up to bout 190 itll run perfect but after that itll will start missing.. I have recently had issues with starting her up in the morning, a few times in the past couple months its taken me about 5 to 10 times of trying to start it up to finally it turning over(all i got was a click, sounded like it wasnt even tryin to turn over, then all the sudden it would start up fine).....
As far as plugs or a tuneup goes... i took it out to my mechanic and he couldnt find out waht was wrong, he said he checked the plugs and they were fine and that he checked the fuel filter and it was clean as hell.... then right after i got it back from him after driving around for 20 or 30 minutes it started it up again...
Also my weatherstripping has been goin bad and it has experienced a few bad rain storms.... could moisture be trapped in the opti or anywhere else that would cause this problem?
As far as plugs or a tuneup goes... i took it out to my mechanic and he couldnt find out waht was wrong, he said he checked the plugs and they were fine and that he checked the fuel filter and it was clean as hell.... then right after i got it back from him after driving around for 20 or 30 minutes it started it up again...
Also my weatherstripping has been goin bad and it has experienced a few bad rain storms.... could moisture be trapped in the opti or anywhere else that would cause this problem?
Pro
Joined: Feb 2002
Posts: 565
Likes: 2
From: Chandler AZ
Re: 94 missing, stutters when hot (johnandblairspolovet)
I would check the O2 sensors. I would be cruising along and it would act as if half the cylinders quite working. After many parts replaced I bought an Auto X-ray scanner and while driving around I was able to see that one of the O2 sensors was not moving like it shood. Replaced the sensor and all is well. At least it was until the fuel pressure regulator went out. It was hard starting and rough running until I unhooked the vacuum line to the FPR and gas came out. Replaced and fine again. Anyway two things to check. Robert :smash:
Burning Brakes
Joined: Oct 2002
Posts: 984
Likes: 1
From: Bergen County NJ
Re: 94 missing, stutters when hot (rspvette)
I would check the O2 sensors. I would be cruising along and it would act as if half the cylinders quite working.
I had the same conditions - would start up and run fine when cold, but would misfire and stutter under load and when hot. It ended up being a O2 sensor that was failing intermittently. It would scan fine at idle whenever I stopped by the mechanic for a quick check. The car had to be driven a while (with the scanner connected) before the problem could be picked up on the scanner. Also about the same mileage as yours.
Thread Starter
Intermediate
Joined: Mar 2004
Posts: 35
Likes: 0
From: Overland Park KS
Re: 94 missing, stutters when hot (sraft)
the only thing that leads me to believe it isnt the 02 sensor is that i have had a few times lately when i tryed to start up my car and it showed no signs of starting up... until all the of the sudden with one of the 10 to 20 turns of the key is just started right up.
another thing leading me to think it is the opti is that i have heard that if ur engine gets wet or the opti gets moisture trapped in it that can cause it to malfunction... reading this i remembered when a friend of mine decided he was going to clean the engine and decided to spray it down with a hose, could that have led to an opti problem?
also would you recommend changing the water pump and opti at 103000 miles or is it something i should let go until its broke?
another thing leading me to think it is the opti is that i have heard that if ur engine gets wet or the opti gets moisture trapped in it that can cause it to malfunction... reading this i remembered when a friend of mine decided he was going to clean the engine and decided to spray it down with a hose, could that have led to an opti problem?
also would you recommend changing the water pump and opti at 103000 miles or is it something i should let go until its broke?
Race Director
Joined: Jan 2002
Posts: 12,264
Likes: 88
From: O'Fallon Missouri
Re: 94 missing, stutters when hot (johnandblairspolovet)
also would you recommend changing the water pump and opti at 103000 miles or is it something i should let go until its broke?
With 100,000+ miles on the car, if you are changing the opti, definately change the water pump.
[Modified by STL94LT1, 1:45 PM 3/3/2004]
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Pro
Joined: Jan 2000
Posts: 523
Likes: 7
From: Austin,TX USA
Re: 94 missing, stutters when hot (johnandblairspolovet)
yep, sounds like the opti. If its 100K miles and has hard, sharp stutters at low rpm with a load then I'd bet money on the opti. This unit is just like any other distributor with a cap and rotor. You'd never think of going 100K on a normal cap & rotor, right? thats probably it. I'm actually doing wp and opti on mine, among other things. If you're doing opti do plugs, wires, and wp. Also consider replacing the opti, crank, and wp seals in the timing cover. they're easy if you have that stuff off. They're also a source of oil leaks too, esp higher milage cars. If you're ordering the parts go to http://samtaylor.com/html/parts.html If after march 10th you'll have to wait a bit since Jason Cromer is moving to a different dealer.
