So I bought an Accord that needed body work and it ran great. The CEL says it needed an new TPS.
I am pretty adapt at working on cars and I actually own a shop. But this Accord is going to be the end of me. Here is it's current situation:

Car will run and drive with the diagnostic computer plugged into the port. I don't even have to turn it on. I have already replaced the computer. Now there are a lot of new parts on this car too. But when I unplug the diagnostic computer it will run really rough. The CEL will flicker but no codes are retained. Also I believe the tach and speedo need replaced. They don't work even with the new vss in there.

Parts done so far are:
Distributor with coil, wires, plugs, map, egr, vss, tps, O2 Sensor, water pump, timing belts and all parts in there, and an alternator.

I am assuming that the crank and cam sensors are okay as they will usually set off the CEL. Only thing I can think of besides that would be the Cat. But I don't see any of the other signs besides the drive-ability.

So if anyone has had this happen before and has some advice, please let me know.

 

I haven't...never even heard of it. Hopefully if someone else has and he'll chime in.

That said, was it the same problem before you replaced the ECU? It seems to me that if it runs well with the scan tool plugged in, then the scan tool is providing something that the computer needs. There are pinouts for that connector around:

"http://pinoutsguide.com/CarElectronics/honda_obd_2_pinout.shtml"

Stab in the dark, but maybe checking pins 4 and 16, ground and +12, with the connector unplugged, might be a start. Possibly an ECU pin pushed out of the connector when the ECU was replaced, and plugging the scan tool in provides whatever the pushed-out pin provides?

 

There is a thread on the internet where the guy's car doesn't run well without the scan tool plugged in. In his case, it turned out to be a ground connection. Probably ground location G101 for his car, as the shop didn't tell him specifically, only said near the intake.

 

So my guy that did the TPS just informs me that he took the intake off to change the TPS. So I will see if there is a missing ground. I'll update you guys later.

 

Not only missing but if loose or dirty it will cause the same type of thing. So even if it is connected I would remove/clean and then attach.

 

Did you replace the ECM w/ exact duplicate of the one removed? Have you checked that ECM in there is original part? Wrong ECU could cause problems.

It ran good before you did all this work? TPS is almost never the problem, but rather a symptom of something else.

good luck

 

Sure enough that was the problem. It was there but it was only finger tight. So once I tightened it up it ran great. Thanks everyone!

 

Glad you got it and thanks for coming back with the answer.....too many time we never know the end of the story. So thanks again.