My 1989 Formula 350 TPI jerks and pulses while holding throttle steady even at slow speeds BUT--runs good while accelerating, even mildly. When holding throttle open in park from idle to 2500 RPM (probably higher too) it misses. New tps, plugs, wires, cap, rotor, fuel filter,OXYGEN sensor and had injectors cleaned through fuel rail. Tested fuel pressure--42lbs. NO improvement. I was reading another post and someone said to unplug the O2 sensor. I did and the car ran great. So I bought another O2 sensor thinking the first one was bad. Put it in and she runs lousey--same problem. I unplugged the connector and the car runs great again. QUESTION: Is the O2 sensor directly related to another specific sensor (note specific sensor) or just the whole ECM system in general? How about incorrect voltage at the connector? Where do I go from here? Please help, really tired in Riverside California. Where's Eddie from Temecula? Saw you at Pick-a-Part.

 

I just had a weird problem with my car. Jumping/bucking/stalling/tach jumping. Nothing I did including 02 sensor helped. The I decided to hook a timing ligth to it and found out that the ignition was actually cutting out on me. I changed the module, pickup coil, swapped coils, no change. But when I disconnected the ESC wire to set base timing the car ran fine. With this wire disconnected it cuts out the computer from controlling the engine. But when I plugged the wire back in the problems started again.

I had went over all connections, weather pack connectors, and grounds. Or, lets say I thought I had went over them all. After two weeks of total frustration I pulled every connector and ground and checked them again.

What I found on the back of the drivers cyl head was a double ground wire crimped into a ring connector and attached to the back of the head with a stud/nut arrangement. The first time I just tightened the nut and no change. The second time I took the nut off and used a lighted magnifier to check the connection. I found corrision where the ring connector was crimped. I cut the connector off, soldered a new one on, and my problem went away completely.

Hope this helps.

 

Thanks for your post Alloy, I will check that but my car runs great when I unplug the elec connector on the 02 sensor. New AC/Delco sensor. I hope to see an answer by this weekend. Surely someone else has had the same problem. To everyone out there, read my orginal post "02 sensor weirdness" I state the problem very clearly. Thanks everyone.

 

I forgot to mention I also got zero output reading from the 02 sensor when I scanned the car with my Auto X-Ray unit. Which could be interpreted as a bad 02.

With no computer ground nothing worked right. But when I disconencted the ESC wire that took the computer, 02, and just about every sensor the computer uses out of the loop the engine ran ok. I would guess you are doing the same thing by unplugging the 02 sensor on your car. You might try unplugging the ESC wire and see if runs like th 02 was unplugged.

Anyway, it's worth checking. Cost me a ton of money and 2 weeks without my car.

 

Some other sensor is probably bad. With the O2 sensor unplugged, your car will run in open loop (car running on pre-set parameters)

When you plug it in, the car goes into closed loop (computer relies on sensor data to adjust how the car runs), and a messed up sensor is causing the car to run poorly.

 

Some other sensor---like what? Is it just a guessing game?

 

Well let me see, the 02 sensor, MAF sensor, MAT sensor, CTS sensor. Probably more, but this is all I can think of now.

Try leaving the 02 plugged in and disconnecting the MAF. This should do the exact same thing, put the computer in open loop and will run the same as 02 disconnected provingto you it's not the 02. And, also disconnect the ESC wire. Will also put the car in open loop limp home mode.

I found out I was losing power to the ignition when I used a timing light and the light went off when I was changing distributors. But with the ESC wire off and the computer in open loop no problem.

The bad ground connection explains a lot of my problems. The engine would shake and the ground would make a breif connection and supply a ground to the computer, then drop the ground connection again shutting off the ignition, then repeat the process over and over again. Also when I'd hit a bump in the road, same thing, shift gear under hard accellaeration, same.

Have you checked that ground wire I told you about yet? I don't mean to nag you, but it's just our problem list is so well matched.

 

Alloy, I found the problem. It was the connector for the fan switch. I replaced the fan switch two months ago when I first bought the car. It's located above the starter in the block or head, I can't tell from the obstructed veiw. Anyway, today I just remembered how the connector was very brittle and it simply failed. I just spliced in a new one and connected the 02 sensor and the car runs good. I checked that ground you mentioned and it was in good shape. Thanks for taking an interest in my car. It's amazing how finding something simple like that can give you a whole new outlook on your car. Especially after so many hours of trouble shooting. After reading these forums I can tell people are like me. They would rather find and fix the problem themselves rather than leave it at the shop and just say, "fix it." Frankly I know without a doubt that I am more careful than any shop I have ever hired. I don't want anyone touching my woman, if you know what I mean!

 

You are welcome for my interest in your trouble. Many, many people here have helped and tried to help me, so I'm just trying to give a little back if I can.

I'm glad you found it. That connector you found bad will be just one more item I'll add to my mental inventory of things that can cause problems like this.

I truly find it amazing how simular our problems were, and how different the solution was.


And yes, I understand. I want them to keep their filthy hands off my lady also I don't make may exceptions to that rule.

 

Alloy, I got alittle ahead of myself. It was ok for a day but I don't think I got it warmed up fully. So the whole thing is unchanged. I just took a test light to the harness part of the 02 connector and got no light. That was with the engine running. That's not right is it?

 

If you're running a one wire O2 sensor you will not get a test light to show anything on the harness. But your scanner should show some output for it. If nothing in the scanner, and 2 O2 sensors show the same thing (any ot them "known" to be good?), then you have a harness problem.

 

Hello VernW
Yes it's a one wire. I don't have a scan tool nor do I know which one to buy. Can you recommend one. Forgive me but I have never owned cars where I needed one.
Here is a little story that might make Camaro owners smile. In 1992 I bought a 1971 Camaro for $200. Neglected, would not move when I put it in drive/reverse, but same owner since 1973 (I think that's usually a good sign.) While I went in to do the paperwork my girl friend went to the store and got 3 quarts of ATF. When she got back I was waiting outside by the car. I put them in and drove the car home. Manual brakes so that was weird at first. I love that car. In May of this year I decided to drive it from Southern California to the very Northwestern corner of Minnesota. My brothers have a large farm there and I just wanted to put it in one of their sheds and store it. Everyone out here said I was crazy to attempt such a foolish thing. Two days later I am on the farm north of Stephen, MN. The only trouble I had was a plug wire came loose so I crimped it with a pair of pliars. I got as high as 22.3 mpg and lowest was 16.6 bucking a wind in Nebraska. I love that car.

 

Sorry I haven't gotten back to you earlier. Been busy buiding a brake kit for shipment.


I think if you plan on keeping this car, a wise investment would be an Auto X-Ray scanner. I think Schuck's sells them. The X-Ray unit isn't as good as a laptop and the Moates scanning software, but it will scan and give you a readout, and I beleive 15 seconds of captured scan data.

You can also go into monitor mode and watch 44 items individually as you drive. One of the items is the 02 sensor milivolt reading. Even though I've got my car sorted out for now, I'm still driving down the road monitoring things.

And, my code 36 wasn't the MAF sensor itself. I had swapped the MAF relay and burnoff relays trying to solve my problem, and one of the wires in the weather pack connector for the burnoff relay was pushed out when I installed the new relay. So, just one more thing for you to check. Make sure all wires are not pushed out of the connectors.

It almost seems like there is no end of things that can cause problems on these cars. But, when they are running right, they are sooooo sweet to drive

 

Alloy, thanks for the post. I will check out the Auto X-Ray scan tool. I'm also interested in the laptop/Moates deal. I don't buy online so where would I look for the software? Would an old laptop from the classifieds be good enough? I plan on keeping the car for a while. Bought from original owner and he took good care of it. 100% stock. Both front fenders and the hood have a factory sticker with the VIN number which matches the title so it has never been wrecked. Not gonna give up. You guys are mastering these cars and so will I. Thanks for the help.

 

I beleive the moates software is still a free download. Do a search for it here.

I'd think a used laptop would be fine, and you either need one with a good battery or a power inverter and a data cable.

I'm not to good at the computer data logging, or chip mod stuff. I'd suggest going to the prom buring forum and asking people more knowledgable than I about this. I tried it and not my bag. Got the chip burner and tuning software, but just not my forte, and have no time to teach myself this without some kind of help to get me started. I'm a machinist not a programmer.

Let me know if I can be of any more help to you.

 

Maybe you want to sell the chip burning equipment? I did some reading about chip burning and bet in reality it is harder than they make it look. I'm a painting contractor. I looked in Autobarn.com and the EZ 3000 is what I need. Wow- $250! I'm sure they are worth it.

 

You can do a lot better by just getting a cheap laptop and using the free TunerPro (or $30 if you decide to register it like I did - got to support the work these guys do!) software.....

 

I like that idea. Would an old laptop Win95 be sufficent? Does it need a CDrom drive? When I buy the cable, what should I ask for or can I make one? Get one at any computer place? I will pay for the software. Is that Moates software? I gotta get in the ball game here. Thanks

 

Sorry for the delay getting back to you, was in a class the last 3 days...

Win 95 would probably be fine, check on Craig's site to be sure. No CDROM is needed unless you want to reload the operating system or upgrade to Win98 or XP (so a good idea to have one if possible). Moates.net has cables, as well as links to the software downloads for data logging. You can't get an ALDL logging cable at CompUSA or local stores, different connector than they're going to have. You can also make your own, several have, but I don't remember the URL for the instruction. You could probably search for it here and find it though.

Does that help answer your questions?

 

Yes it does. Moates.net says I need a ALDL cable 1 $30.00 but won't work without ALDU 1 $50.00. Still going through the classified in home paper for laptop. How often does a TPS go out?