[solved] LH-2.4 running issues

jamesinc · 2018-04-03T12:29:12+00:00

Hi James... some ideas for you: 1. Check for air leaks in the exhaust prior to the O2 sensor. 2. Check for air leaks on the inlet side? Injector O-rings? ma...

jamesinc

I could pull the injectors from the 850R, but maaaaan am I hesitant to touch my only other functioning car!

Slowbrick

Do you have 12v to your O2 sensor heated wire?

Philia_Bear

@jamesinc

The symptoms may be the same but the cause could be different

I've had new plugs fail after a week, just bad manufacture

Also... your not running a resistor pack I assume?
I've got spare good injectors if u want yet more parts :-)

Really really dumb one... but have u checked cam belt timing
And or could it be a bad crank sensor

jamesinc

Okay so I put fresh plugs in and put the "wrong" AMM back in and it now runs nice.

Ill come back to this thread as I want to get to the bottom of what's going on here, but I'll be a while as I need a goddamn break from cars

Slowbrick

jamesinc;133866 wroteOkay so I put fresh plugs in and put the "wrong" AMM back in and it now runs nice.

Ill come back to this thread as I want to get to the bottom of what's going on here, but I'll be a while as I need a goddamn break from cars

What happens if you put in the right AMM?

Hearing you on the need a break from cars bit too :(

jamesinc

Slowbrick;133867 wrote
jamesinc;133866 wroteOkay so I put fresh plugs in and put the "wrong" AMM back in and it now runs nice.

Ill come back to this thread as I want to get to the bottom of what's going on here, but I'll be a while as I need a goddamn break from cars
What happens if you put in the right AMM?

Hearing you on the need a break from cars bit too :(

It runs fine at first but gradually I think fouls everything up

deleted_user_2040

Have you got a spare AMM you can try for good measure

jamesinc

volvotragic;133873 wroteHave you got a spare AMM you can try for good measure

Yeah, two, they both produce the same result, I think.

jamesinc

Now that it runs I realised I can actually take good readings from the O2 sensor. I'm also going to drop the cat out and see if it's blocked. There was a LOT of soot in the exhaust from the old engine running poorly, probably enough to supply Ad Reinhardt for his entire career.

DW42

Given that you got a slightly high reading when you tested the FPR, have you tried switching it out for one you know is good? A faulty FPR will make it run rich, badly, and will foul the plugs.

jamesinc

DW42;133924 wroteGiven that you got a slightly high reading when you tested the FPR, have you tried switching it out for one you know is good? A faulty FPR will make it run rich, badly, and will foul the plugs.

Not yet. The O2 sensor is what I want to dig into first.

timbo

What brand 02 sensor did you get?

jamesinc

timbo;133934 wroteWhat brand 02 sensor did you get?

Bosch OE sensor

jamesinc

Sensor is reading tiny values, like 15mV at idle.

Still not prepared to point the finger at the sensor. Next I am going to do a backpressure test on the exhaust

jamesinc

Okay, I've resolved it. It feels good when your gut instinct is on the money.

The issue turned out to be a short to ground between the O2 signal wire and pin 5 of the ECU. Years ago when I re-pinned everything, I separated out the O2 signal from its shielding to pass it through a connector. I didn't tidy it up very well it seems and when that wiring was disturbed recently it's joined and gone to ground. So I re-did the wiring, fixed the short, and then was seeing a steady 0.54V. What I want is a moving voltage, not a steady value, so I took it up to Pie in the Sky and then thrashed it down and up Old Pac and I'm now seeing good signal. The rich smell in the exhaust has also dissipated, so I think we're good!

Philia_Bear

jamesinc;134123 wroteOkay, I've resolved it. It feels good when your gut instinct is on the money.

The issue turned out to be a short to ground between the O2 signal wire and pin 5 of the ECU. Years ago when I re-pinned everything, I separated out the O2 signal from its shielding to pass it through a connector. I didn't tidy it up very well it seems and when that wiring was disturbed recently it's joined and gone to ground. So I re-did the wiring, fixed the short, and then was seeing a steady 0.54V. What I want is a moving voltage, not a steady value, so I took it up to Pie in the Sky and then thrashed it down and up Old Pac and I'm now seeing good signal. The rich smell in the exhaust has also dissipated, so I think we're good!

So it was the O2 sensor..... for all the wrong reasons

jamesinc

No, the sensor it turns out was fine, the wiring harness at the ECU end was the issue.

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