Dreaded CEL

Ditch the Champions and install some NGKS! Seriously.

The chips you have now will indeed set codes and turn on the CELs when appropriate.

I was under the impression that the rough running started with the chip installation. If not then forget what I said about reinstalling the old chips. The engine should run better/smoother than stock with the new chips. I was thinking that perhaps other mods had been made to the engine in order to work with the aftermarket chips and that was the reason for the rough running, but apparently not?

 

No. David received a set of chips copied from OEM code. Although the processing speed is faster than the OEM chips, they will absolutely display error codes. His aftermarket chips were throwing a CEL, at least he has a stock baseline now from which to continue troubleshooting.

 

I would change out those plugs and re-learn the ECU. I had a couple times when fouled plugs were causing me lots of headache.

 

Sounds to me like either one or both of your ECU engine temp sensors are dead, or the connection(s) are bad. When the temp sensor circuit is open the ECU thinks that the engine is below 0F, so it really dumps the fuel in to compensate for the dense air.

Do you still have converters on the car? If so, use an IR temp gun to compare the surface temps of each converter. If one is notably hotter than the other that probably means that bank is running rich. In that case, check the temp sensor and fuel pressure regulator for that bank.

 

There's one for each bank. IIRC. That's why it'd be nice to know which bank you should be looking at. See the diagrams on the Ricambi site or in the parts manual for the locations. I'll see if I can dig up an image in a minute.

 

I'm pretty sure that one is located at position 43 in this pic. The manual calls for two, but apparently does not indicate the position of the second one. Seems like it would be in the same position on the other bank though.
Image Unavailable, Please Login

 

Good work David!!!

Super chips has been around for a while. Whether you gained anything from those is unknown, unless you have a dyno pull from before you swapped out the eproms. Then you could do a follow up dyno, at the same shop, and see what the difference is between the two.

 

Awesome thread. Eric is great!

I agree with the post that recommends using Bosch replacements only. While you're waiting for them to arrive I'd suggest dousing the contacts with DeOxit, since there's a decent chance it's just a bad connection (especially if both are acting up). You can also perform a basic test by checking the actual resistance versus the specified resistance (presumably stated in the repair manual). What really matters is the resistance that the ECUs see-- if there's resistance in a connection the ECUs can't calculate the correct mixture, even if the sensor itself is fine. So testing the resistance at the ECU plug is the preferred test method.

Good luck!!!

 

The coolant temperature sensors should measure about 2 K.Ohm at about 25C, more at lower and less at higher temps.

If removing the coolant overflow hose from the housing, carefully check the hose adaptor (aluminium). Mine was like on the 1st pic below - condition after cleaning out the accumulated crude (it wasn't leaking as it was almost completely plugged). Solution is on the second pic.
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Brass fitting 1/4 BSPT, 10mm hose barb. Sources of coolant temp sensors:
Image Unavailable, Please Login

 

The cheapest genuine Bosch I can see on Ebay (US) is $18 - New Engine Temperature Sensor Bosch 80254074101 | eBay

 

Wow-- one of the rare parts for our cars that are actually cheap. No doubt because it is used in other applications. At that price I think I'll pick up a couple to install during the upcoming major service, just for good measure. Thanks, Miroljub.

 

Assuming you mean the "crossvalve" between the two manifolds. Because the only way a throttle butterfly can be stuck on a 348 is if the throttle linkage fails... because it's a mechanical throttle, just as God intended.

I'd have to go back and read this thread more carefully to be certain, but IIRC the symptoms you describe point toward a rich condition, which most often means a bad CTS or a bad FPR.

 

Coolant Temp Sensor/Fuel Pressure Regulator.