Thread: CEL issue

Last couple of times I drove my car, the CEL came on. The radiator fan comes on as soon as the key is turned to ON too. It did this at first when I installed an OBDII stepdown to OBDI, but then the CEL went away after a while, and all was good. Now, it comes on almost every time I run the car, except rare occations.

At first, I thought it was the CTS since the fan came on before the engine was started. I just put a new CTS in before I did the stepdown. Are the sensors the same for a B13 and a B14? I have a 2" aluminum radiator, and the temps do stay lower than with stock.

I checked my O2 sensor, and it's starting to get carbon buildup from the A/F's being so rich. At startup, my wideband reads around 14-15, but after the engine runs for about 10 seconds, the a/f's move to 10 and beyond. Only at slight throttle (up to 12%), do the a/f's stay correct. At about 13% to 15% throttle, the engine bogs down bad. But it is only at this small range of throttle position. At 15% to 44% throttle, the a/f's stay rich as hell. Beyond 45%, the a/f's drop steadily as throttle and airflow increases. Also, at idle, it fluctuates between 600 to 950 rpm.

I know the MAF is good, so that leads me to the O2 sensor, or the CTS that would cause this, but both are new. Anyone had a problem like this? The car runs, but is burning WAY to much gas like this. Plus, with it going lean at higher throttle, boost is not an option. And that sucks.

Any ideas?

Can you go back to OBDII temporarily to determine whether you can associate the problem with the OBDI conversion? That might give you some insights.

Not really. I won't have any way to account for the injectors or different maf.

OBDII scanners won't work. Wouldn't some shops have a way to pull codes from the consult port? Maybe then I can find out what the issue is.

What ecu are you running? I had the same exact problem with my B14 and it turned out to be a bad chip. Or so I am pretty sure it was, haha. Moisture in the ecu?

It's a B13 NismoTronic with a basic board and OBDI stepdown. The chips don't seem bad. I always verify after burning, and have never had a problem. I did check the board header, and anything else I could see for loose connections. Checked wiring harness, plugs, etc.. I can keep turning the key on and off until I don't hear the fan start. Then I can start it and everything's fine. But once I turn it off, it's a crap shoot wether or not I can get it to work right again.

I DID notice one thing today. When I turn the key and the fan and CEL comes on, I don't hear the fuel pump prime, nor do I hear the ECU relay click. But it will still start and run. It runs rich as hell, but it runs. AND, if I get on the gas pedal, the a/f's lean out like the FPR isn't working or something. When I can get it to start without the CEL or fan coming on, I DO hear the fuel pump and ECU relay.

any resolution to this problem?

No. There is only one place in town that has a consult scanner that will pull codes for free, and every time I swing by, they are always too busy to get to it.

I can cycle the ignition on and off, and eventually it will work right. Sometimes it takes a second, sometimes it takes up to 4-5 minutes. :/

What you're describing (when it goes into the fans turn on immediately, car runs like butt mode) is the ECU not booting up correctly. When it's in this mode it's not actually using the daughterboard. You can verify it's in this mode easily- turn the key to the 'on' position but don't actually start the car. Listen for the fuel pump to come on, and then it should turn off after four seconds (this assumes you're letting the ECU control the fuel pump and haven't hardwired it or something of course). If it turns off after four seconds the ECU has booted properly, if it doesn't follow this sequence, well, it hasn't.

When it's in the 'bad' mode a consult handtool will not communicate with the ECU.

I would guess you've either got something bizarre going on with the daughterboard, ECU core, or a really funky noise issue. Make sure you're grounding the chassis of the ECU (so just bolt it in place like it would be normally, I'm going to guess that since you're using a step-down you've just got it dangling in there). Beyond that check the step-down to make sure all the ground wires are actually getting good connections. After that I would replace the ECU core and daughterboard in that order.

Good luck.

^^ welcome back?

First of all, it's good to see you around again!

I keep cycling the ignition until everything comes on correctly. I NEVER run it it the "butt" mode. Sometimes the fuel pump and other relays will turn on, even with the fan coming on. But I just keep trying until it works right.

At first, I did have the ecu bolted down. But yes, now it's just tucked away under the console. The fuel pump is still connected in the stock manner. If it is a ground issue, would it be okay to tap into the intake mani ground? (I re-grounded the manifold) Or where would be the best spot?