Need some advice on engine trouble

[thenuge876]

My 86 T/A stalled out on me while I was driving one night and I took it to a shop to get it fixed adn it turned out to be a couple of wires that overheated adn had worn through. So they fixed those adn also attached a couple of wires (i believe to the battery) that were previously unattached, i had noticed this before but since the car had ran fine for almost 10,000 miles i did not see it as a problem. Now that they have fixed the problem and connected the wires the car runs "really rough". I have a replacement 305 in the car (that i did not put in myself but was done by a mechanic) so the timing on the distributor was different. When they fixed the distributor timing the engine still ran rough and at this point the shop seems to be unable to tell me whats wrong. Any advice would be appreciated, and also could those battery wires they connected have anything to do with the engines rough running condition? Thanks.
-Dan

[Mark B]

Disconnect the battery wires and see if it runs better.
They may run to an old accessory that isnt in use any more. Regardless, I would want to know where those wires run.

[thenuge876]

Thanks for the help

Thats what i told the guy also, he didnt say they were went to anything inparticular. The were just grounding wires he said. But thanks for the reply and ill mention that to him when i speak to him next anyway.

[N20LT4Bird]

If they were ground wires to the body or something of that nature, that would make the car run rough. But, this obviously isnt your problem since the car still runs poorly.

Is this a T.P.I. motor or throttle body?

Your problem could be one of many different things ranging from bad igntion components, to vacuum leaks, to sensor issues (MAF, ECT, MAP etc..), to fuel pump or injectors/regulator. "Running rough" is a very broad term.

The first thing I do is determine if the problem is air/fuel or spark related. Usually you can tell by the way the engines running. You can determine if you have a dead miss by disconnecting the plug wires one at a time until you pull one and it doesnt make difference in the way it runs. Timing should also be checked.

I would also scan it for codes and watch the values for the key sensors (ie. MAF/MAP, ECT, TPS, etc) A fuel pressure test may be in order to rule out the fuel pump or watch for stuck injectors or regulator issues. If the problem doesnt lie there, it could be wiring issue or the PCM may be at fault as well.

[thenuge876]

Thanks again

The engine is T.P.I. model, it's a Jasper replacement engine for the car, the trouble i recently found out seems to be wiht the firing. The mechanic said something about my firing order was different adn he wasn't sure why, so it seems to be spark related, but they have the timing all set, only when they did that, it still wasn't running right. The reason I had mentioned the wires, is because when i replaced the battery a while back, i noticed that there were wires not connected, and when i had it in the shop since that is what the service manual said, adn since the guy worked for GM for a number of years, he connected them. It ran fine without them connected, adn now that they are it's not running properly. I figured i'd ask becuase I wasn't sure if it was just a coincidence or not. Thank you for the reply...the help is really appreciated. What other problems could there be with the spark? Do you know why the firing order might be different? Thanks.
-Dan

[TraceZ]

The engine is T.P.I. model, it's a Jasper replacement engine for the car, the trouble i recently found out seems to be wiht the firing. The mechanic said something about my firing order was different adn he wasn't sure why, so it seems to be spark related, but they have the timing all set, only when they did that, it still wasn't running right. The reason I had mentioned the wires, is because when i replaced the battery a while back, i noticed that there were wires not connected, and when i had it in the shop since that is what the service manual said, adn since the guy worked for GM for a number of years, he connected them. It ran fine without them connected, adn now that they are it's not running properly. I figured i'd ask becuase I wasn't sure if it was just a coincidence or not. Thank you for the reply...the help is really appreciated. What other problems could there be with the spark? Do you know why the firing order might be different? Thanks.
-Dan

Small Block Chevy firing order is 1-8-4-3-6-5-7-2. It has never changed as far as I know, even the LT1 is the same.

They changed it for the LS1, though.

[DeWynter]

But there is a more efficient firing order. 18726543 its used on the vortec 8100

[N20LT4Bird]

I would be inclined to disagree with your tech. If the car was running fine, then started to stall out and then run rough, how can it be the firing order? Spark plug wires cant move from one plug to another. Now, they can fall off or get burnt and then, if not installed properly, could mess up the firing order. Or.....if it was the first time starting the motor after major work or something, thats a different story.

I would be looking for something worn, burnt, broken etc.

TraceZ is right.....1,8,4,3,6,5,7,2 is the firing order for your car, unless some major engine/ computer mods have been done to change it to an alternative firing order.

[thenuge876]

thanks again

There were wires that had overheated adn burned through which is why the car cut out on me. But when the guy was putting it back together he connected some grounds that weren't connected before (and oculd have been the reason for overheating), after he did that the car wasn't running right, so they checked the distributor timing adn made sure it was all zeroed out, adn it still wasn't running right. It seemed they were at a bit of a loss as to what might be cusing it, which is why ia sked about the ground wires, firing order...etc. But thanks for the help, i think he has the firing order for it now. Thanks for all the help, hopefully ill have my T/A back soon!
-Dan

[thenuge876]

FINALLY!

Well it seems as if we found out what the problem was. The guy said I "have a 370 timing cover on a 350 block". I don't really know what that means so if anyone would like to give some info that'd be cool. But he seems to be well on his way to fixing my engine now and said he might have it done by tomorrow. Sooo all is well i think for now. Thanks for all the help.

[N20LT4Bird]

I dont know about the 370 timing cover bit. Ive never heard of a 370. If he looks on the scanner for the timing, it doesnt matter what timing cover is on the engine....

Tell the tech that there is a wire that must be disonnected to set the timing on those T.P.I motors. SOmeone correct me if im wrong (going by memory), but I think its a single brown wire in the passenger side of the engine compartment up by the fire wall. Theres a connector that must be disconnected so that the ECM doesnt try to compensate as you move the distributor around.