backfire through intake, little acceleration
Thread Starter
|
Junior User
Joined: Jul 2003
Posts: 54
Likes: 0
backfire through intake, little acceleration
I have an '89 Ford Ranger, 6cyl 2.9L. When I give it gas and try to accelerate, it boggs down, has little power, and then backfires through the intake. The codes that I am getting are 77 and 74, Operator error on balance test and brake. No help there. I did a fuel pressure test and got 35 psi and have also been able to rule out the pressure regulator with a vacuum pump. I disconnected one sensor at a time and no improvements. My #4 cylinder pressure is down to 50 psi and a wet test shows that it is the piston ring. The cylinders are out of balance when spark plug wires are removed ona at a tim, but could that be the problem? If you could give me some advice, I'd be really stoked... Thanks....WoodstockAz
Thread Starter
|
Junior User
Joined: Jul 2003
Posts: 54
Likes: 0
backfire through intake, little acceleration
Checked the timing and found no degree markers, but since it is specified to be 10* BTDC and the mark was right on the pointer, it must be 10...Right? I also noticed a mounting bracket next to the pulley with nothing on it, and I'm thinking it is a timing sensor that is missing...does the '89 Ranger 2.9L have a sensor there?
Posting Guru
Joined: Jan 2003
Posts: 1,061
Likes: 0
From: Still under the hood in O
backfire through intake, little acceleration
This may sound stupid but.... My sister once had a Cavalier that would backfire through the intake when you gave it gas. If you held the gas down steady it would backfire on every stroke. We assumed it was a lean pop and went from there as we were new to EFI at that time. After replacing every sensor and even the computer we found the problem. It was a simple oversight of a bad plug wire. The reason we weren't convinced it was ignition related is it ran so smooth at idle. So don't overlook the obvious as we did.
The problem I see is the compression on the one cylinder, that is not good at all. With the backfire through the intake and the low compression I would be thinking burnt intake valve.
If you have an air compressor, get an adapter to screw into the plug hole of that cylinder. With it at TDC on the compression stroke screw in the adapter and turn on the compressor. Listen for the air leak. (Preferably with a long hose with the compressor as far away as possible)
If you hear it through the valve cover it is a valve. If you hear it through the oil pan it's rings. Either way, that needs to be addressed.
Let us know what you find. Good luck!
The problem I see is the compression on the one cylinder, that is not good at all. With the backfire through the intake and the low compression I would be thinking burnt intake valve.
If you have an air compressor, get an adapter to screw into the plug hole of that cylinder. With it at TDC on the compression stroke screw in the adapter and turn on the compressor. Listen for the air leak. (Preferably with a long hose with the compressor as far away as possible)
If you hear it through the valve cover it is a valve. If you hear it through the oil pan it's rings. Either way, that needs to be addressed.
Let us know what you find. Good luck!
Thread
Thread Starter
Forum
Replies
Last Post
FX4-350
1987 - 1996 F150 & Larger F-Series Trucks
38
Mar 26, 2014 08:46 AM
92RangerDude
1983 - 2012 Ranger & B-Series
17
Apr 9, 2010 05:00 PM
Craigmire
1973 - 1979 F-100 & Larger F-Series Trucks
26
May 1, 2009 04:29 PM
Icicle
Big Block V8 - 385 Series (6.1/370, 7.0/429, 7.5/460)
32
Oct 4, 2005 02:01 AM
