Been working on a del sol project for a friend. When we picked it up we knew the engine ran rough, the cel was on (41-o2 sensor), and the guy didn't have a clue what he was doing. We put a new o2 sensor on it along with plugs, plug wires, cap and rotor, and cleared the CEL. Now it is still running rough it is firing on all four but runs like it's misfiring. The ignition timing is good, cam timing is good, tried my working dizzy, and the CEL is gone. I'm running low on ideas here. Anyone else got some? I think I'm going to put new grounds on it tomorrow to see if that helps. :dunno:

 

loose engine harness ground to the thermostat housing?

Chassis grounds bad?

Loose connection to ecu?

hook up your tuning equiptment & datalog it to find out which sensor might be giving off false info! Might have not just stopped working & there for not throwing a code, but giving off false info causing it to run like crap.. Definatly check map sensor & TPS

 

I'm gonna replace the ground straps tomorrow. I think I will do some datalogging to see if something is just fudged up. I still think it's a bad connection or something at the dizzy since the tach isn't working. Thanks Tony.

 

The ECU needs a tach signal in its engine management calculations. If the tach signal isn't making it back there, expect weirdness. When you used your diz, you said the CEL went away, but did it run right? If not, probe the ECU harness' CAS signal wires to the ECU. The wiring diagram is on my old civic page if you need the pin numbers.

 

the CEL went away when we put a new O2 in it, nothing changed when we put my dizzy on it. I put new ground straps on it yesterday and the tach came back. Now it just wants to fall on it's face while taking off. we tried a new fuel filter and it got a little better. it feels to me like it's not getting the right fuel. hooked up my ecu to datalog a little and all I saw was the TPS looked a little flaky but when we got out the voltmeter and checked it was fine. I gave him a spare throttle body with a good TPS on it for him to try. it's just got some gremlins we need to hunt down.