Rough running and little power

[87mefull]

I think it varies with which gas station I use, but I know the gas in Philadelphia is of very poor quality. My friends 93 GM with 74k cannot run on 87 octane at all either, his car actually died and wouldn't restart a block after he filled his car up with it once too. Same thing happened to my blazer (2.8v6 designed to run on 87) also, I had to keep my foot on the gas at stop lights to keep it running. I thought I could get away with running it since I was using a gift card and 93 was at 2.66 a galon.

Timing is at 10BTDC and I'm not throwing any codes. I just ran some seafoam through the PCV and the brake booster, so it might be able to run again on 87. I have run 87 octane up by my school with an additive, but with the harsh roads here I actually get better gas mileage running 89 octane.

[Tiggie]

I know what you mean about the cruddy 87. My mom's '87 T-Bird 5.0L has never run well on 87 Octane, and she's had it since new. Nothing has ever been messed with as far as timing or engine mods (not even the intake or valve covers have ever been removed), and it will ping it's brains out on 87. On 89, it only does it occasionally at a low rpm load. My '82 will run on 87 fine, but it's got lower compression than ya'lls EFI motors I think.

[gadget73]

Mine really likes Hess gas for some reason. Does not like Sunoco fuels. No idea why but I consistantly get worse fuel milage on Sunoco gas.

[87mefull]

Mine really likes Hess gas for some reason. Does not like Sunoco fuels. No idea why but I consistantly get worse fuel milage on Sunoco gas.

I filled my car with 87 at Sunoco and thats when I started having alot of problems. I don't think I'm ever going to Sunoco ever again.

[LTDMan83]

I run 93 exclusivly in my Box for just that reason,noticably much less carbon and sludge buildup takes place in the engine.Also gets better gas mileage and a little extra power over 87.

[Grand Marquis GT]

Sunoco is junk.