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Poor drivability , long 900 1994

This may be long-winded, sorry. I have explored the FAQ's and checked the items I thought could pertain but still have the problem.

A few months back, with the car running as well as it ever has, I lost coolant due to a heater hose blowing out. The gauge pegged high. I took the opportunity to do a major tune-up; hoses, plugs, cap, rotor, NOT wires (they are less than 2 yrs old, Bougicord), RPM sensor, T-stat, I-manifold gasket, cleaned TB and other assorted items I deemed needed replacement at 200K. After the tune-up, the car drove from Atlanta to the Gulf Coast w/o a problem. While on the beach, it began to run poorly (misfiring) at idle and low speed acceleration but got me home to ATL. I ran the codes and the ECT came up as a poor or missing signal (1-2-3 in socket 2). Since it was right in the line of the original hose failure squirt, I cleaned & inspected the connections (they were filthy/corroded), tested the resistances of the sensor and reconnected. Everything seemed fine for a few days, I was able to clear the trouble code which I could NOT do before I cleaned the contacts.

I am again experiencing the misfiring, it seems to occur most often under boost when starting up from a full stop or accelerating to pick up speed to pass or merge. It seems fine when I am travelling at a constant rate no matter what the speed (30 mph or 70 mph) and only manifests when I try to accelerate. No codes are recorded, I get 1-1-1 out of both sockets 2 and 6 of the "A" connector. I also should note, it seems to run fine when still cold and only starts acting up when the engine has reached operating temp. Could the ECT have been damaged in the original overheat and be giving intermittent false readings that would cause these symptoms?

I am now also thinking about the O2 sensor (it is the original, yes, I said the original) and thinking about the AMM but am loathe to drop $$$ on expensive parts only to find they are not the culprit. So I thought I would set this out there for anyone with greater knowledge of the system than me. I tested the O2 sensor using the propane torch method and it did pass that rudimentary test, producing appropriate voltages and dropping off rapidly when the heat is removed. The check engine light has NOT come on at all since I cleaned the ECT contacts. I do not see/hear any arcing from the plug wires. All my intake hoses are in good shape as is my PCV system (breather box & associated plumbing)

Things I have NOT done include a compression test, leakdown test, and fuel pressure check. Lastly, my daughter took the car up to UGA for the week (anyone know a cure for that?) so I cannot play with it this weekend and will have to wait until Christmas break.

Thanks in advance...

K
--
Bob Kraushaar '94 945T, '91 940T(retired), '88 240, '84 242Ti, '94 F-150, '88 300TE, '89 560 SL, '68 Shelby GT-500 KR






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New Poor drivability , long [900][1994]
posted by  rjk  on Fri Dec 3 12:47 CST 2004 >


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