Mechanics

ENGINE STUTTERS WHILE UNDER ACCELERATION.

1988 Mazda b2200

Engine Performance problem
1988 Mazda b2200 4 cyl Two Wheel Drive Manual 573000 miles

I love my truck and just spent about 4 grand doing an engine overhaul, bored, rings, bearings, hoaned an all that good stuff. Well like my father always told me, " Once you change things from stock, it'll never run the same or last as long.&Quot;

I've come to realize this. I live in Oregon an the state doesn't require smog emmisions so I got rid of it all except for the catalitic converter. The other day I noticed that when under full acceleration that the engine tends to putter and choke. Thought it was the cat so I took it out and sure enough it was almost completly plug up. Now it's clean an just another piece of exaughst. But it still is stutter and sounds almost like it's loading up. But once at a higher rpm it stops, seems like it's the begining of every gear.

I've traced all vacum lines an are connected and not sucking excess air. Timing is dead on, an the vacum advance is working. I've only modified the exaughst to a straight through design and the intake with a taller air filter. It's been fine for almost two years like that and just started. Oh an I also replaced the 02 sensor.

Could it be from the exaughst being straight through without the stock backpressure? I'm lost. Any suggestions will be appriceited. Thanks

Cody
Avatar
Shortspaz97
February 5, 2009.



A little backpressure is good fo ra stock engine. This has a carb? Check spark quality out of coil adn out of distributor, should be blue not orange. A weak coil can cause hi-rpm misfires. Has the carb ever been gone through? (Rebuilt)

Tiny
Jack42
Feb 6, 2009.
Yes it has a carb/w an electric choke and I haven't rebuilt it in a while. It has new plugs, wires, and coil and the spark is a very thick blue spark. It runs great at higher rpm. Just the begining of every gear does it stutter and choke.
When I floor it in first, and second it stutters and shakes but once over about three thousand rpm it quits. Some times it doesn't even do it in third, forth or fifth.

Thanks for you help, I'm kinda a car guy myself an this just stumps me. Lol. Not many things I can't fix an it's driving me crazy.

Tiny
Shortspaz97
Feb 6, 2009.
Forgot to mention that if I accelerate slowly or not all the way to the floor it doesn't do it at all. An the choke is working, let it warm up an watched the butterfly open up. Thanks again.

Tiny
Shortspaz97
Feb 6, 2009.
Have you used a timing light to see if the distributor is advancing correctly? You said all smog is gone, does this include EGR?

Tiny
Jack42
Feb 6, 2009.
Yes, I used a timming light an yes the egr is gone as well. I had headers put on two years ago when I did the rebuild and got rid of all the smog stuff. I'm thinking it has to do with the carb some how for it ran good for two years without a problem. Has great compression, doesn't smoke but the exaughst does smell a little rich. I also got a new o2 sensor today thinkin the last one was bad but it's still acting up.

Tiny
Shortspaz97
Feb 6, 2009.
Sounds as though it may be a little rich down low in the rpms. May be due for another rebuild

Tiny
Jack42
Feb 6, 2009.