Car backfires and gives up @4800rpm,HELP?
11-22-2001 | 08:29 AM
#1
Thread Starter
Junior Member
Joined: Jan 2000
Posts: 41
Likes: 0
From: monroe,Ga. usa
Car backfires and gives up @4800rpm,HELP?
when I get to about 4800rpm in any gear it starts to backfire and stuggle. I have to let off and let it shift then it runs fine. I changed the fuel filter. has new plugs and wires. It sounds to me that the ignition is giving up because of the backfire. I have been told that these have a rev limiter in them, but 4800 seems to low for that. The car is an 88GTA 350. I had an 85 IROC that didn't do it so the rev limiter dosen't seem viable to me. HELP
11-22-2001 | 08:35 AM
#2
Supreme Member
Joined: Jan 2001
Posts: 7,164
Likes: 1
From: Someone owes me 10,000 posts
Car: 99 Formula
Engine: LS1
Transmission: T56
Axle/Gears: 342
Check your timing. Where is the backfire, in the intake or exhaust. If exhaust check for a clogged cat. Also make sure you're not running too lean.
------------------
"Putting any amount of money into a RICE BURNER is like wiping your a$$ with a turd. "
'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
3" Hooker CatBack w/Aero Chamber muffler
EDELBROCK 600CFM CARB.
KN AIRFILTER
ACCEL HEI DISTRIBUTOR
160* Stat, just switched to 180* b/c of winter coming and going to college in the mts.
3:73 Posi
Rebuilt 700R4
B&M Megashifter, 5" Autometer Tach w/shift lite
------------------
"Putting any amount of money into a RICE BURNER is like wiping your a$$ with a turd. "
'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
3" Hooker CatBack w/Aero Chamber muffler
EDELBROCK 600CFM CARB.
KN AIRFILTER
ACCEL HEI DISTRIBUTOR
160* Stat, just switched to 180* b/c of winter coming and going to college in the mts.
3:73 Posi
Rebuilt 700R4
B&M Megashifter, 5" Autometer Tach w/shift lite
11-22-2001 | 08:40 AM
#3
TGO Supporter
Joined: Jul 1999
Posts: 10,907
Likes: 3
From: The Bone Yard
Car: Death Mobile
Engine: 666 c.i.
There is a rev limiter, but in the stock eprom it is basically disabled (set to around 10,000 rpm). So if you have a stock eprom, that is not your problem.
How's your ignition coil? If it is old and the original, it may be "saturated" and not able to provide any spark at higher rpms. Also, did you change the cap and rotor?
The pickup coil in the distributor may be another source of problems, though it tends to cause a bit of a mis-fire at all rpms if it is not working properly.
On a car that I owned many years ago, weak valve springs caused valve float that made the car do basically what you are experiencing. It wouldn't rev past 4,500 rpm.
How's your ignition coil? If it is old and the original, it may be "saturated" and not able to provide any spark at higher rpms. Also, did you change the cap and rotor?
The pickup coil in the distributor may be another source of problems, though it tends to cause a bit of a mis-fire at all rpms if it is not working properly.
On a car that I owned many years ago, weak valve springs caused valve float that made the car do basically what you are experiencing. It wouldn't rev past 4,500 rpm.
11-22-2001 | 06:41 PM
#5
Supreme Member
Joined: Jan 2001
Posts: 7,164
Likes: 1
From: Someone owes me 10,000 posts
Car: 99 Formula
Engine: LS1
Transmission: T56
Axle/Gears: 342
<font face="Verdana, Arial" size="2">Originally posted by rallysport:
It is in the exhaust and the cat is gutted. I did a search for this problem and that 4800rpm came up alot. Most of the talk is that the TPI just peters out.</font>
It is in the exhaust and the cat is gutted. I did a search for this problem and that 4800rpm came up alot. Most of the talk is that the TPI just peters out.</font>
------------------
"Putting any amount of money into a RICE BURNER is like wiping your a$$ with a turd. "
'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
3" Hooker CatBack w/Aero Chamber muffler
EDELBROCK 600CFM CARB.
KN AIRFILTER
ACCEL HEI DISTRIBUTOR
160* Stat, just switched to 180* b/c of winter coming and going to college in the mts.
3:73 Posi
Rebuilt 700R4
B&M Megashifter, 5" Autometer Tach w/shift lite
11-22-2001 | 06:56 PM
#6
Supreme Member
Joined: Oct 2001
Posts: 1,392
Likes: 4
From: orlando, fl usa
Car: 1986 pontiac TA
Engine: 360 HSR
Transmission: 700r4 3300 yank converter
Axle/Gears: 3.27 9 bolt
<font face="Verdana, Arial" size="2">Originally posted by rallysport:
when I get to about 4800rpm in any gear it starts to backfire and stuggle. I have to let off and let it shift then it runs fine. I changed the fuel filter. has new plugs and wires. It sounds to me that the ignition is giving up because of the backfire. I have been told that these have a rev limiter in them, but 4800 seems to low for that. The car is an 88GTA 350. I had an 85 IROC that didn't do it so the rev limiter dosen't seem viable to me. HELP</font>
when I get to about 4800rpm in any gear it starts to backfire and stuggle. I have to let off and let it shift then it runs fine. I changed the fuel filter. has new plugs and wires. It sounds to me that the ignition is giving up because of the backfire. I have been told that these have a rev limiter in them, but 4800 seems to low for that. The car is an 88GTA 350. I had an 85 IROC that didn't do it so the rev limiter dosen't seem viable to me. HELP</font>
11-22-2001 | 08:01 PM
#7
Supreme Member
Joined: Dec 2000
Posts: 1,536
Likes: 0
From: Springfield, MO, USA
Car: 1986 Trans Am, 1991 Firebird
Engine: 355 TPI, 3.1L V6
Transmission: 700R4 in both
My stock TPI 305 died at 5k so I wouldn't worry 'bout that part too much. The backfire and loss of power could be related to a wore out O2 sensor.
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