Changed Relays - now idles bad and dies

[mhanch]

Well, I did something.

I was swapping out my old relays for the newer Purple Bosch ones, and the Blue Lambda relay (same as Delorean Industries sells, or DeLorean GO) and once back together it would start, but the idle was terrible and it would die. even giving some gas it just dies. I swapped the old Lambda back in and same thing. (disconnecting battery each time)

any ideas what I messed up?

[Bitsyncmaster]

Check your lambda relay (main fuel relay) that you have the correct one installed and that none of the pins pushed out of the socket.

[CFI]

any ideas what I messed up?

Yes. You used old school relays instead of using Bitsyncmasters’s high tech solid state relays:)

[DMC5180]

Well, I did something.

I was swapping out my old relays for the newer Purple Bosch ones, and the Blue Lambda relay (same as Delorean Industries sells, or DeLorean GO) and once back together it would start, but the idle was terrible and it would die. even giving some gas it just dies. I swapped the old Lambda back in and same thing. (disconnecting battery each time)

any ideas what I messed up?

Did you happen to install a relay in the floating empty socket in the back of the relay area?

[Jonathan]

When was the last time you had it running and idling nice and normal? Right before the relay upgrade work? Or was there anything else you worked on, tinkered with or adjusted in between?

[mhanch]

It was fine just before. So definitely one of the relay changes was off. I didn't add anything to the empty socket in back. I'll check the connection pins next. Sounds a likely culprit.

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[mhanch]

OK, checked the relays and installed the original Lambda relay in the yellow socket. Pushed underneath, and no wires are loose.

It fires right up, runs ok for about 10 seconds, then starts to stumble. the rev's jump up to about 1200, then fall again, and stumble. it does this for about 2 minutes, then dies.

Next thoughts?

[Bitsyncmaster]

OK, checked the relays and installed the original Lambda relay in the yellow socket. Pushed underneath, and no wires are loose.

It fires right up, runs ok for about 10 seconds, then starts to stumble. the rev's jump up to about 1200, then fall again, and stumble. it does this for about 2 minutes, then dies.

Next thoughts?

Yes the yellow socket is the Lambda relay. Are you sure you installed the old lambda relay? It was the one relay that is different from the others. Usually it is a lower profile unit (not as high as the other relays).

I'm 99% sure your problem is with that lambda relay circuit. When you pull the relay out of the socket do you see all 5 pins in the socket?

A faulty lambda relay will change your engine mixture so that sounds like the problem you are having.

[mhanch]

Yes, it's the shorter relay with the Black X through the top. I kept it separate from the others. I see 5 sets of wires below, all are attached tightly.

The new relay that I was going to replace it with was this: https://www.amazon.com/gp/product/B004Z0TRPA/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1 - same unit Delorean Industries sells: https://deloreanindustries.com/12-relay-lambda-probe/

and the schematic on the relay matches the one on the old relay. So it looked like a straight swap. is there a fuse to look for, or maybe Do I need to pull the relay again and try to clean the connectors on the inside?


PS: thanks for the help so far. Bummer when a bit of preventative maintenance turns into a project on it's own. :)

Edit: attached image of the relay schematic on the relay. I may have read it wrong.

[Bitsyncmaster]

Yes, it's the shorter relay with the Black X through the top. I kept it separate from the others. I see 5 sets of wires below, all are attached tightly.

The new relay that I was going to replace it with was this: https://www.amazon.com/gp/product/B004Z0TRPA/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1 - same unit Delorean Industries sells: https://deloreanindustries.com/12-relay-lambda-probe/

and the schematic on the relay matches the one on the old relay. So it looked like a straight swap. is there a fuse to look for, or maybe Do I need to pull the relay again and try to clean the connectors on the inside?


PS: thanks for the help so far. Bummer when a bit of preventative maintenance turns into a project on it's own. :)

Edit: attached image of the relay schematic on the relay. I may have read it wrong.

Did you replace the RPM relay? The RPM relay has two outputs. One drives the lambda relay and WUR heater and the other output drives the fuel pump. I have seen a few NOS RPM relays not drive both outputs.

[mhanch]

No, I didn't touch that. Just the Changeover relays and the Lambda.

[mhanch]

Just trying to think of anything else, are there any connections in the engine bay that I should check if they are loose? I'm wondering if something was just marginal and the change made the signal too weak. I' try to keep things clean in there - and I'm wondering if i might have bumped something so it was just a bit loose.

Yeah, grasping at straws.

[Bitsyncmaster]

Check if your frequency valve is buzzing. If it is than the lambda relay is powering both the FV and lambda ECU. I have to say if your engine is not running correctly after changing the relays your mixture has changed. Engine has to be running.

[mhanch]

Would a different relay change the mixture? And is that something I can correct fairly easily?

In either case, I'm going to revert all the relays until it's sorted out.

[mhanch]

OK, all relays are reverted back to previous. connections all feel solid. I started it up and it ran, I could head some buzzing from the Freq Valve, but it seemed to get quieter after a bit, but the engine still was rough and then died. Do I need to adjust the mixture now? Not sure why this would not revert back.

Also it looks like i don't have the open port for that on top of the fuel distributor. I'd hope there's something non-invasive to do at this point.

EDIT: i should note, it was not doing any big surging to 1200 rpm this time. just a real wobbly idle. perhaps that's better? does it just need to be driven to burn off the extra gas if the mixture was bad for those starts? Or sit for a bit?

[Ron]

I'd would rev it a bit and run it at a high idle to clean up the plugs/cylinders. If that improves it any, go for a ride.
You shouldn't have to do anything with the mixture, although checking it with a dwell meter might give you a clue.
Then if all good, put the new relays in one at a time...

[mhanch]

...and we are back to normal.

I checked a few other threads about rough idle, and took the opportunity to clean the electrical connections in the back that are connected to the Lambda system. Everything was pretty dirty, so I hit each connection with contact cleaner and a fiberglass pen. Once I put it all back together, I cranked it over and revved the engine a few times. It blew out some fairly nasty unburnt gas vapor, and took a bit to settle down, but started to idle again. Then I drove the freeway a bit and heated everything up. Running great, back to normal, and the idle is steady. Actually smells a bit better than before, so it may have been a bit rich before. I'll save the rest of this project for the summer when I can get time to do it bit by bit.

Thanks for all the help!