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Hello Everyone,
Car starts rough, but after after 30 seconds or so, runs well. Because I am a beginner, I have not yet learned how to properly diagnose the problem. I could use some help. The car is a 93 sedan with 113K on it.
Start up is without question rich, as engine shakes and putt-putts and exhaust smells rich at startup rpm's. We have another 93, so I have been swapping parts without any success in isolating the problem. Once the car is warmed up, it starts up fine. However, it does have a bit of a dance: When it starts, rpm goes to 1400 rpm (I'm guessing - no tach) then heads down, then goes back up to 1100, then down, then settles at proper 800 rpm idle. This procedure goes on for about 2-3 seconds. The other 93, at startup might get to 1100 rpm initially, then drop to idle promptly. So the two are different. I hope this hasn't confused the issue, but I thought I'd mention it.
Swapped parts include: AMM, IAC (clean as a whistle)and ECU. I have cleaned the throttle body and snorkel tube and have checked for vacuum leaks using the propane method (with some cardboard blocking the radiator) at injectors, near the intake gasket, around the snorkel tube and connections at AMM, and vacuum lines, all without any noticeable difference in rpms. I have smell tested the FPR vacuum line and it smells clean. There are no codes, and all the swapped out parts work fine in the other car - and the other car starts perfectly so I know something is not right. My friend Rich believes it is leaking injector(s) that forces the engine to run overly rich at startup. I have run a tank of 93 octane and some techron fuel injection cleaner through without any noticeable difference in startup. One thing I have not swapped out is the ECT. Do you think that it could be the problem? Keep in mind that after about the first 30 seconds, the car runs fine. Gas mileage on trips averages between 25 to 27 mpg.
Today was the first time I got into the 951 ECU (to swap it - which I did) but I couldn't figure out how to undo the connector to access the pins where I could check continuity and resistance per Bentley. Do you think I should head in this direction? I would truly like to diagnose vs swap parts.
I'm kind of perplexed and could use some help if someone has some knowledge to spare.
Marty Wolfson
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93 244 185K, 93 244 112K, 93 245 116K (in California now), 99 V-70 89K
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Hello My Friends,
Just to followup. Figured out how to get the connector off, although I think I will wait for warmer weather to figure out how to access the pins for system testing. I did swap the ECU to no avail. I also ran through the self diagnostic procedures shown in Bentley for the fuel injection and ignition system with no faults evident.
After a couple of weeks of fooling around, trying this and that, it appears my rough idle has been eliminated. As my friend Rich, the mechanic, suggested, "unclean" injectors. After running a tank of 93 octane along with Chevron Techron Injector cleaner, the car seems to start and idle properly.
Thanks for your thoughts and suggestions.
Marty Wolfson
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93 244 185K, 93 244 112K, 93 245 116K (in California now), 99 V-70 89K
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Hello Marty:
I have very minimal knowledge, and certainly very little to spare, but if I am able to help in any way, it would be a good thing. I had a Toyota act somewhat you describe at one time, and new plugs, wires and dist cap solved it. I guess it was having a problem lighting off the cold mixture. The others I would check would be the ECT resistance at the ECU, and also checking of the TPS at the ECU. Maybe it ( the ECU) thinks it is at WOT, and is dumping extra fuel and oscillating the IAC.
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Gary Gilliam Sumerduck VA, '94 940 na Regina 160k '86 240 190k, 93 Camry 4cyl 5spd 245k
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Hi Marty,
Your "problem" (more like a "condition"?) is of such short duration, with no apparent negative side effects, that it's hard to think of anything that you haven't already swapped or checked.
To measure ECT and wiring resistance at the ECU, you need to take the connector apart, per Bentley page 241-11. As I recall, you need a good light to see the terminal numbers.
As a random technical guess, try removing and cleaning the 3 ground points shown on Bentley 390-6. Can't hurt, and I think the front-most one is for the ECT. But that may have been for LH 2.2.
Well, this will at least put your query back up in the running for a while.
Good luck,
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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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