Strange problem

dono200sx · Nov 13th, 2005, 11:22 PM

This problem has a couple friends and myself baffled. Not sure what is causing it.

This happens at all speeds, different temperatures, whether driving hard or easy, and on the freeway or streets. I haven't been able to single it out to anything specific like that.

While driving, the car loses at power. It starts bucking and sounds like it is backfiring out of the intake (loud popping noise). The motor will not rev and you have to floor it to maintain speed. It's almost like the computer is keeping it from revving or there is something mechanical or other wise that is getting stuck or clogged thus restraining the motor. It almost seems like the computer is retarding the timing or went into limp mode.

It comes out of no where lasts for less than a minute, and is gone as quick as it comes. One time I had to pull over into a parking lot and let her sit for a minute before I could drive again. It happened last night and I floored it to try and maintain speed (on I-635 during a busy part of evening). It went away pretty quickly.

I know it's hard to troubleshoot this sort of problem without being there in person, but I'm willing to chase down any possibilities. Could it be something like the EGR valve or Air Indiuction Valve? Thanks for the help!

dales86t · Nov 15th, 2005, 01:22 AM

Checked timing? sounds like the timings reatrded to the max! changed a belt lately? or pulled the dizzy? changed CAS? also check for vac leaks.

RocketRodent · Nov 15th, 2005, 06:38 AM

Quote:

Originally Posted by dales86t

Checked timing? sounds like the timings reatrded to the max! changed a belt lately? or pulled the dizzy? changed CAS? also check for vac leaks.

Failing or clogged MAF.

Zen31ZR · Nov 15th, 2005, 08:10 AM

MAF problems don't go away by magic. I'd suspect plug wires, possibly. Have you kept an eye on the temp guage during all this?

A sticking EGR might cause this problem, as well as a sticking air valve. You can pull the units off the side of the intake manifold and try to clean them up.

dono200sx · Nov 15th, 2005, 11:13 AM

The plus and wires are new. I have NGK plugs with Bosch wires. I have not been able to find anyone in Irving, TX who sells NGK wires other than the dealer. And they want an arm, leg, and my right eye for them.

The MAF is a rebuilt one from NAPA.

The timing has been kind of crazy. It seems that it is changing on me. I can set it and the next time I go to check it it will have changed. I have a feeling the dizzy was removed at one point, though it hasn't been since I've had the car. In order to get it to 22°BTDC I had to turn the distributor clockwise and peg it against the screw. I was not able to get it to 20°BTDC. (so right now I am running 89 octane to try and keep it from pinging) Any ideas on that that is happening?

I do not know of any vacuum leaks. One of the first things I did was start replacing all vacuum hoses. I'll double check that again tonight and make sure there wasn't anything that I missed.

While checking the hoses, I'll take a look at the air valves and see how they are. Am I able to use carb cleaner for that as well?

Thanks for the help!

Zen31ZR · Nov 15th, 2005, 02:06 PM

When you set timing, you have to disconnect the Idle-Up solenoid on the driver side of the intake manifold. I assume you are doing that? You may not be getting an accurate set if that is not done. At that point, check your idle speed. Should be 700 rpm in neutral with a manual trans, or 650 rpm in drive with an A/T.

At that point, timing should be 20 + or - 2 degrees BTDC. That could be 22, and it could also be 18.

RocketRodent · Nov 15th, 2005, 09:08 PM

Have you taken a look at the crank to see if it has twisted? I know this wouldn't go away but it might be worth a look.

dales86t · Nov 15th, 2005, 10:17 PM

Its the distribuitor, CAS or plug leads. Make sure ALL of the plug leads are on the right plug, pull dizzy out when engines at TDC. take off field plate on distribuitor under the cover under the rotor, take out the WHOLE Crank angle sensor unit, look under neath, clean all the corrosion off (yes it does corrode under there! big cause of misses) then RESET your distribuitor as per FSM, when you have it set roughly the car should start and idle fine. then you may time your engine as per manual.

if its not that, id be checking the AFM for sure!

dono200sx · Nov 19th, 2005, 11:00 AM

Update: Yesterday I took the air valve of the car and cleaned it up with some carb cleaner. It was pretty gummed up with carbon and junk. Took a couple minutes to get it completely clean again. It made a very noticeable difference once it started up. The motor revs more freely and fells like it has a little more power according to a "seat of the pants" test.

Tomorrow: EGR valve. I'll let y'all know what happens.