Hey guys, well I just got my 91 T/A back from the mechanic a couple days ago (all 8 injectors replaced). The thing was running pretty well the past couple days, but it felt like it was vibrating a tad hard at idle. So while taking her for a very short spin today the idle was harder than usual, the whole car was trembling and there was an annoying squeak/click coming from the interior which eventually faded away. So i figured that something was up, at first I thought the wires got a little wet from rain (yesterday was nice dry and warm, about low-mid 70s) since today was a wet and dreary day (high 50s-low 60s and kinda humid). But this thing felt like it had only 7 cylinders.... the throttle response wasn't quite there. It actually bogged for a split second when I punched the gas and it felt like it could respond better.

So I did the plug-disconnecting trick off of the cap and turns out #8 ain't firing... or is barely. I have a little ignition tester so I took a wire that I know is good from my other car (94 Jimmy) since the #8 is sooo hard to pull out unless you get under the car... which I wasn't doing. So I plugged in that wire into the #8 prong on the cap and i plugged the tester into that and I realized that it sparks, but not always. When it's idling it'll won't spark for a second or two at a time about every few seconds and when I hit the gas it cuts out even more, but it's pretty consistent when I let off the gas while the rpms are dropping but same story once it returns to idle.

I'm assuming that the mechanic screwed something up while working on it since while diagnosing it he said that he replaced the distributor thinking it was a spark problem but put the old one back on when that turned out to be not the problem (bad injectors)

I'm gonna argue with him, but what do you guys think is wrong with it?

 

Nothing yet? Here let me simplify the problem: #8 is hardly firing. Ignition tester revealed that spark is very inconsistent at idle and works a few seconds at a time every few seconds. It's even worse when getting revved but the spark becomes consistent when the rpms are falling to idle, once it hits idle the same thing happens.

I'm thinking its a bad cap? I managed to shock myself twice while testing this (go me) and I remember that the shock was kinda strong when I got too close to another wire but it was a little weaker when I got too close to the #8 prong... any pointers?

 

I would replace the cap, rotor and wires if it was me.

 

Are those basically the only possibilities? Is there anything else that might've gone wrong? And I doubt that its the wires, since I used the ignition tester with a different wire, one which I know is good.

 

It's more likely the #8 plug is fouled.

 

I HIGHLY doubt it... if you read my post, you would see that I wrote that I used an ignition tester on the #8 terminal on the cap and it was giving a weak spark. And the plugs are all brand new with about 12 miles on em. And I used a different wire which I know is good for the tester so I know that it's not a bad ignition wire either.