no shift at WOT
Jun 8, 2004 | 07:52 PM
#1
Thread Starter
Teching In
Joined: Nov 2002
Posts: 10
Likes: 0
From: Baton Rouge, LA
no shift at WOT
98 Chevy Z71 with 5.7L and 4L60e. When I floor it, the engine will rev to either 3000 or 4000 rpm and nothing further and it won't shift for a few seconds (until the truck slowly reaches proper mph). It feels as if the transmission is slipping but the engine is not taching out. I brought my truck to my transmission guy and he says it's not transmission. By the way, after changing my front O2 sensors, the problem didn't occur as often. I've got Thorley headers, Volant intake, Gibson exhaust. Any suggestions as to what may be causing this?
Jun 9, 2004 | 12:21 AM
#3
Thread Starter
Teching In
Joined: Nov 2002
Posts: 10
Likes: 0
From: Baton Rouge, LA
Low to mid throttle, the truck drives and shifts fine. Because the problem is erratic, I haven't been able to pinpoint the exact conditions since sometimes it happens when the engine is hot and and sometimes when cold. Also, the truck feels like it has lost some low end power.
Jun 9, 2004 | 01:22 AM
#5
Thread Starter
Teching In
Joined: Nov 2002
Posts: 10
Likes: 0
From: Baton Rouge, LA
umm...I'm pretty sure it does this in every gear. One time I went to pass another car on a two lane road and it did this...that was kinda scary for a second. I thought it might be the Hypertech, but I unprogrammed everything and it still does it. I put headers on my truck and now that I think about it, the problem started after I installed the headers...
Jun 9, 2004 | 01:47 AM
#7
Thread Starter
Teching In
Joined: Nov 2002
Posts: 10
Likes: 0
From: Baton Rouge, LA
Almost positive that nothing was disturbed during install, but I will check up on that in the morning. I asked a mechanic about it and he said that it could be numerous different things....improper fuel/air ratio, low fuel pressure, something faulty in the ignition system, etc. So tomorrow I will change fuel filter. I guess I should get it hooked up to AutoTap.
Trending Topics
Jun 9, 2004 | 02:39 AM
#8
TECH Junkie
Joined: Mar 2003
Posts: 3,271
Likes: 0
From: Katy, TX
Right now my Blazer does the exact same thing. It drives 100% fine at normal throttle, but WOT it jumps to @4k and wont climb any more. Sometimes it even slows down at WOT. My guess is its my spark plugs. It never did this till i gave it a tune up. New plugs, wires, and cap. The plugs are gapped way high though. Like .100-.090. I didnt have a gapper handy when i swapped them.
My suggestion is to just change your plugs and gap them at .040. The added fuel and air flowing into the cylinder can prevent proper spark, causing it not to rev right.
My suggestion is to just change your plugs and gap them at .040. The added fuel and air flowing into the cylinder can prevent proper spark, causing it not to rev right.
Jun 13, 2004 | 07:00 PM
#10
Thread Starter
Teching In
Joined: Nov 2002
Posts: 10
Likes: 0
From: Baton Rouge, LA
I changed my fuel filter and the problem hasn't come back yet! I'm gonna change the spark plugs(~35k miles on AC Delco Platinum) and that should help the truck out. I changed the filter not too long ago and yet it got clogged pretty quick. I've been putting FRAM fuel filters on there but now I believe I'm gonna change to another brand. Anyone have any flow data on fuel filters?