94 LT1 is sick please help

[mbigd73]

i have two problems one if i drive my car for say 10 miles it starts to miss at low rpm like when you first leave a red light it gets pretty bad till you get above 2000 rpm then it runs ok also the trans is 3 months old when you first get in it it will shift fine but after you stop it will not shift right its like first and od arent there but if you let it sit for a while it will shift fine again till you stop same with the missing if you let it sit for awhile it will run fine for awhile any help would be great thanks

[KnightFire]

The first problem sounds like a burned plug wire to me. As for the 2nd, how is the ATF fluid level?




KnightFire

[msbzlt1]

sorry to tell you this but my car had same symptoms and it was the opti, does it surge at idle like the tach goes to 1500 rpms just setting still in park..

if it does my bets its the opti...i tried to fix my problem with many solutions before opti, but only wasting my money.

i replaced spark plug wires, coil, iat sensor, the 02 sensors then the opti was the thing that fixed it last fix before I was going to give up

Good Luck

[mbigd73]

thanks the atf is at normal level have not checked plug wires yet it does not surge at idle but it does miss a little as far as transmisson goes iam lost thanks a bunch

[Joe 1320]

Since the trans is electronically controlled, a real time scan of what is going on would be the ticket. Could be a valve or hydraulic problem. If the trans is only 3 months old, isn't it under warranty?

[mbigd73]

thanks

thanks for the help the problem was the fuel pump we checked it it only was puting out 4 psi after driving for a little while at idle it was at 10 psi it went out to day we also put a scaner on it for the trans and it gave a no kick down code and a silonoid code but thanks for the great help yea the trans is under war but the guy was being a jerk and said its the way i drive that i tore it up again so my lawyer will bring the car to him monday the guy swore up and down i had nos on the car it is bone stock aside from a flow master and k/n filter but not for long thanks again

[Torque]

thanks for sharing the results. Oftentimes, people bring up a problem, people offer a bunch of advice, and then nobody ever hears what happened.

Everyone blames everything on the opti. I just replaced mine, only to find it was not the issue. Having a new one does not hurt anything though!

[mbigd73]

if it helps any body i am glad because just changing parts is for the birds and very costly and i do hope this can help someone

[Torque]

In reference to "replacing parts for the birds", I completely agree, however, I make myself feel better about it by thinking about how many fewer parts I have to replace after I replace them....

One less part that will break soon!

[Sean 94z28]

Here is my take:

This seems to be a single VERY common symptom for a variety of problems on these cars. Especially the LT1s. This seems to be a logical way to diagnose.

1. Scan for codes if you have access to a scanner (try Autozone if not). All codes do not put up an SES. Fix Codes according to service manual.

2. Watch the engine run from above and below in the dark, and look for arcing around plug wires and coil wire. Eliminate arcing.

3. Quadruple check wire routing if you just did any repairs that caused you to disconnect ANY ignition wires.

4. Check fuel pressure. Ohm out coil. Ohm out coil wire (or borrow friends coil and/or wire).

5. If you only have performance problems after warm up (suspect o2 sensors or heat soak on a failing coil).

6. if you have near 50,000 miles on the opti, begin to suspect this is your prob (esp if you have a 93-94 and/or water is or was "weeping" from the pump).

7. If everything checked out at this point and you still are not ready to change the opti. You can start pulling and inspecting plugs and checking for spark at each cylinder. Compression check for high milage or abused engines.

Everything still seem ok? At this point you can probably go ahead and change the Opti if you have more than 50k. Even if it is not the primary problem, it likely will be soon, or is a contributor to overall poor performance. If you have less than 50k or are really on a budget, try to find a friend who has a full function engine scanner. Not to look for codes but to monitor the engine while driving in real time. Also post details of your findings and we will try to help.

Experts: please correct, add, flame my list where required!

Sean

Remember too, a bad opti pretty much runs bad in open and closed loop (hot or cold engine).

If you also have problems at high RPMs, be sure to check for restricted exhaust first (pretty much high milage applications also).

[mbigd73]

yep i agree 100% .there are a lot of things to look at . i mean parts can get pretty pricey if you take your time and ask qestions and trouble shoot it can save you money and time thanks for info