B2600i performance parts

Hi I'm a new member and just bought a 93 B2600i. It only has 84000 miles on it, it turns over fine, but there is no compression. I pulled the rocker cover and the timing chain appears firm and there are no binding issues. How do I determine if this is a valve timing issue? Any help or suggestions would be appreciated.

I think no compression would be a head gasket problem... does your oil look like a chocolate milkshake when you check it?

Hi eddiep23,

I kinda though about that , but wouldn't that apply to 1 or 2 holes? there's no compression an all 4 cylinders! Oil looks fine.

any compression at all? does air even move out of the spark plug holes if you crank it without the plugs in? Could be a bad head, bad/missing pistons, or timing is way off.

:doh: all four?? rings maybe? or yeah, a bad head like crazy said

Yes thanks crazy. I took the truck to a mazda service dealer and they said its the bypass valve. That unit runs approx $650. Too much for something that small that goes attached to the throttle body.. I'll see about picking it up at a dismantling yard or something. If I get lucky.

Found one on eBay for $90 bucks. (thanks for the advise "91 2600i"). Installed it and it does the same thing. Incorrect diagnosis by the Mazda dealer. It looks like to me they don't even know the cause of this. They had to call Mazda themselves and still same problem. Lost faith in them. Anyways, my next option is to look into this switch on the tranny like "befarrer" has stated. And yes it does exactly as you stated but with but with a low idle (almost turns off) after a quick accellaration and then corrects itself. I hope its not the computer and more like that sensor or something else in between the sensor and computer/IAC valve. I'm still open for any advise. I have to say, this blog/forum is pretty cool. Very helpful tips and info by good people. Thanks guys.

does it seem to start running real rich when the idle drops and it almost dies...? can you smell the presence of gas fumes? i've had a similar issue that sounds like yours, but mine runs rich and smells fuely... i still havent solved my problem yet...

i've found that on these trucks its a two piece exhaust manifold, and the seal between them gets worn out (probably due to age). I simple replaced mine and now that all of the exhaust is going over the o2 sensor, its not running as rich, but still rich

mine was doing the same thing yall are describing and i took my ecu out took the cover off and it was all corroded looked like it was burnt up so i bought a new one installed it and all my problems were solved runs perfect now check you ecu these trucks have problems with copacitors leaking and corroding everything *9-