89 S-10 How to force open loop operation

Is there a way to force the engine computer to run in open loop mode on a 89 S-10 with automatic and the 4.3L? I thought I read how to do it somewhere a year or so ago.

Reply to
Ashton Crusher
Loading thread data ...

Disconnect the oxygen sensor.

Reply to
aarcuda69062

Bigger question is why??

Whitelightning

Reply to
Whitelightning

I'm trying to sort out a drivability issue at higher RPM and just want to see if it runs any different open loop when it's warmed up.

It seems to run out of steam at higher rpm and so it doesn't go fast enough to shift to the next gear when it's floored. If feels like it's not getting enough gas. You have to let off on the gas to let it shift and then it has good power again. I've replaced the injectors and regulator, the TPS, the EGR, the temp sensor, the O2 sensor, plugs, and a couple other relatively cheap parts. The fuel pressure was within specs but I'm still thinking fuel pump. But that's a lot more work to replace then the other stuff... but I can't think of much else. Oh, swapped out the engine computer too, made no diff. Doesn't really feel like an ignition issue, it's not like it's got a stutter like it's missing.

Reply to
Ashton Crusher

possibly a plugged cat. does it make any strange hissing noises?

Reply to
ScottM

Lots of hissing noises, but he's in the litter box now and things seem to be moving again :)

Reply to
Battleax

take it to a muffler shop and have them do a pressure test on the cat. they'll drill a small hole in the neck of the input of the cat and put a pressure gauge in it and can tell if you have the proper flow or if it is plugged. I have friends that own a muffler shop and hang out there. Have seen many s-10 trucks with plugged cats. A lot of the cats break inside and if you bang on it you can hear the substrate rattle. Chunks of it will turn and plug the outlet. I can tell right away if it's plugged without a gauge because the exhaust will whistle out of the hole drilled in the cat input.

Reply to
Meat Plow

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.