Misses at 4k rpm. Please Help!

[eoseitz]

I have a 1990 Laser RS Turbo. I recently replace the turbo with another stock 14b. While I had it up on the lift I decided to remove the catalytic converter. The car ran fine all the way home, however, now it isn't running so great.

When I first start the vehicle is hear a clicking from behind the cd player. I'm assuming its the ecu resetting. When I take it up the road the car will sputter at around 4.5-5k rpm. I have a radar detector in the car that has a volt meter on it. I noticed the voltage on the car is jumping anywhere between 13.5-10.9 volts.

I checked to make sure the battery terminals are tight and that I didn't knock any wires loose on the alt. Could this problem be due to my alt going bad, the missing catalytic converter, or my ecu going out. It worked great up until the turbo/cat job.

Thanks for any suggestions.

 

[r1991_4g63t]

id say either a loose belt or bad alternator

 

[eoseitz]

I did notice a little bit of play in the belt. Is the tension of the alternator adjustable? I'm wondering if I could have moved it a bit when I was installing the turbo or putting the heat shield back on. I don't hear any belt noise though.

 

[r1991_4g63t]

you might not hear any noise but i'd tighten the belt a little bit and see if that helps any

 

[eoseitz]

where is the tensioner located for the alternator belt. I haven't owned the vehicle long enough to change belts. I'll definitely do that tonight.

 

[r1991_4g63t]

its kinda hard to explain, give me a couple minutes and ill take a pic of mine

 

[r1991_4g63t]

first loosen the one that points toward the fender and also the one where the alt actually bolts to the block, which i couldnt get my cam in to get a pic of, then tighten the bolt facing toward the radiator, then once its tight enough tighten the other two back up

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[eoseitz]

Thanks for the info and the pics. That helps a lot. I'll test that out when I get home. A friend of mine also mentioned fuel cut. I'm only running 87 octane. He said even stock I should be running 92. I didn't really consider this. I've never reached fuel cut in a car, but it does kind feel like people describe.

 

[r1991_4g63t]

you NEED to run a premium fuel whether it be 91 octane or higher, your probably not hitting fuel cut as 87 octane would knock ALOT and retard the timing

 

[eoseitz]

Well I put premium fuel in the tank and added some octane booster hoping that would help with the remained of the fuel in the car. Seems to be helping. It didn't miss nearly as bad on the way back to work. Still does slightly, but I'm hoping its just burning off what's left in the lines.

The voltage seems to be staying constant now at 12.5 volts. This is really strange. How would octane rating effect the voltage? I'll go ahead and check the alternator tension when I get home just in case.

 

[r1991_4g63t]

even with the booster that 87 is still probably only 88 or 89, run that gas out and filler up again and you should be good as far as the misfire. as for the alternator, octane wont affect it, i think its just a coincidence.