Drivability Question

[2ndtimearround]

My 86 GW with TFI upgrade starts very easy, idles very well and cruises very smoothly up to 65 - 70 mph (never had it any faster :D )

When I am pulling away from a stop it hesitates slightly, like it is lugging, but accelerates with a slight ping with a bit more pedal. It does this both cold and hot. Acceleration at speed is not very responsive either.

I am wondering if you experts out there can give me an idea what to look at. I am hesitant to just jump in, since the truck starts so easy and runs so well. Or is this the way it is supposed to be?

Lawrence

[RWalker]

Have you checked your timing?

[BK]

Higher octane gas is for vehicles that ping. Newer vehicles adjust timing automatically when they start to ping. Yeah check the timing and try better gas I would say for starters.

[joe]

I'd start with checking the timing also. Don't waste your money on higher octane fuel. Even if it did help some it's just masking the real prob. There is no way a motor with only 8.25 comp ratio needs anything other than the cheapest gas you can put in it.

[Stuka]

the 80's 360's had lower compression then the 70's? I thought they where all the same? I know the inside of the door on my cherokee calls out for 91 RON.

[joe]

Originally posted by Stuka:
the 80's 360's had lower compression then the 70's? I thought they where all the same? I know the inside of the door on my cherokee calls out for 91 RON.Not much lower. It dropped from 8.5 to 8.25 in 1974.

[Stuka]

hrm...everything i have read shows that at least up to 78 the 360/401 had 8.5:1.

I spose I could calculate the compression readings I got from mine and see what they comeout to be in terms a ratio. My lowest was 147.5, highest was 153, and thats with 167k miles on it.

I do know my cherokee runs TERRIBLE on 87 octane gas. It misses and has noticably less power. (this may be more noticable because of the altitude)

sorry for sorta sidetracking the post. I also say check your timing.

[Mikel]

Stuka, as Joe said, a vehicle with 8.5 CR or less, should not need high octane gas. You shouldn't even see a difference from running high octane. My 78 Cherokee (360) seemed to run fine on 87 octane smile.gif

[joe]

Originally posted by Stuka:
hrm...everything i have read shows that at least up to 78 the 360/401 had 8.5:1.
Those numbers I gave you Stuka are from the factory TSM's. In any case it's not enough of a change to make any diff anyway. ;)