780 Bertone (PRV) Idling issue and some engine issues.

Moyni · 11-19-2020, 10:45 PM

Car is running super rich (see sparkplug image), has a funky idle where it seems fine in drive but when its in neutral / park it will surge the RPMs. Doesnt want to rev over 2500 without shaking like the space shuttle Columbia. I just did new spark plugs, wires, rotor and cap.

Thinking try a new MAF and a fuel pressure regulator possibly. I also havent ruled out a vacuum leak.

JohnLane · 11-22-2020, 12:42 PM

Pull the vacuum signal off of the fuel pressure regulator.... Fuel in that one? It may drip out or you may just smell it in the hose... Happens.

Coolant temp sensor and/or wiring to it. Ohm meter across the CTS... Open = pig rich.

Air mass meter much less likely; though everything about it is pretty old.

Give her a set of fresh plugs too. I'm fond of Bosch H6DC.

Check for vacuum leaks as doing so is good practice...Though a vacuum leak won't make her rich like this.

84B23F · 11-23-2020, 12:35 AM

Quote:

Originally Posted by Moyni

Car is running super rich

As John noted, Coolant temp sensor...ohm spec it...in vintage GM vehicles, they go rich when they start failing..

Moyni · 11-24-2020, 05:07 PM

Quote:

Originally Posted by JohnLane

Pull the vacuum signal off of the fuel pressure regulator.... Fuel in that one? It may drip out or you may just smell it in the hose... Happens.

Coolant temp sensor and/or wiring to it. Ohm meter across the CTS... Open = pig rich.

Air mass meter much less likely; though everything about it is pretty old.

Give her a set of fresh plugs too. I'm fond of Bosch H6DC.

Check for vacuum leaks as doing so is good practice...Though a vacuum leak won't make her rich like this.

Ill give these a look, plugs are fresh too, should have mentioned that. Luckily we still have a few scattered NOS B280 parts laying around in the deep dark corners of the shop I can throw at it.

Moyni · 12-01-2020, 01:03 PM

Anyone have a diagram of where the CTS would be? I have the Haynes manual as well as the Volvo Green manuals but still cant find it based off the online part numbers.

This is the only sensor I have seen and I dont believe this is it

84B23F · 12-01-2020, 03:41 PM

Looks like a similar location for a 85-88 Pontiac Fiero...below the thermostat...either for the dash gauge, or for the ECU.

Google for ECU sensor...and compare:=_

84B23F · 12-01-2020, 03:51 PM

Footnote - If your thermostat is open, it should be replaced...this could skew temp readings by ECU.

Also, you most likely found the ECU's temp sensor...

dalek · 12-01-2020, 04:20 PM

Quote:

Originally Posted by Moyni

Luckily we still have a few scattered NOS B280 parts laying around in the deep dark corners of the shop I can throw at it.

Nice, for a while I wanted a B280. So I am glad someone is keeping the flame

Moyni · 12-01-2020, 04:51 PM

So after talking with the bossman here in the shop, and doing some of our own research on the ol VIDA, it does seem like that is the sensor I need to replace. I am sort of firing the parts cannon at this motor in hopes of resolving this, however I still need to pull it back inside the shop on a slower day and take my time testing all the electrical components.

84B23F · 12-01-2020, 06:06 PM

RE: firing the parts cannon

Replace coolant thermostat and coolant temperature sensor...Current CTS has been in there for "ages."

84B23F · 12-01-2020, 09:21 PM

Bosch LH-Jetronic 2.2 fuel injection....most likely then CTS

84B23F · 12-01-2020, 09:44 PM

Footnote - If there is a cold start injector, then that circuit/injector needs to be evaluated.

tomasss · 12-02-2020, 05:07 AM

Quote:

Originally Posted by Moyni

Anyone have a diagram of where the CTS would be? I have the Haynes manual as well as the Volvo Green manuals but still cant find it based off the online part numbers.

This is the only sensor I have seen and I dont believe this is it

Yes, that is the CTS

84B23F · 12-02-2020, 05:51 AM

Quote:

Originally Posted by tomasss

Yes, that is the CTS

Not quite...that CTS has not been evaluated in years/years....nor has its terminals been cleaned up with spray contact cleaner.

OP: With LH 2.2, there should be new CTSs available

tomasss · 12-02-2020, 09:24 AM

Quote:

Originally Posted by 84B23F

Not quite...that CTS has not been evaluated in years/years....nor has its terminals been cleaned up with spray contact cleaner.

One way or another, THAT is the CTS. It's condition is another thing, but the part has been identified correctly.

84B23F · 12-02-2020, 12:32 PM

Quote:

Originally Posted by tomasss

part has been identified correctly.

On a CIS DeLorean, that would be a THERMOTIME switch...iitem #24.

tomasss · 12-02-2020, 04:43 PM

...are we discussing 780 or DeLerean here?

I've replaced this temperature sensor on my PRV too so I remember it quite well.

84B23F · 12-02-2020, 05:35 PM

Quote:

Originally Posted by tomasss

...are we discussing 780 or DeLerean here?

Potential parts for the V6 PRV Parts' Cannon...

Moyni · 12-07-2020, 04:03 PM

Quote:

Originally Posted by tomasss

One way or another, THAT is the CTS. It's condition is another thing, but the part has been identified correctly.

Yeah the book calls it a thermotimer, but I was able to get a new Bosch one for about $20. Seems to have fixed the terrible rev issues it had, however it still has a seeking idle. I can unplug the MAF and the idle stays the same so I have a buddy sending me a new (used) MAF to test with. If that works, I should be able to take it out on the street for the first time since I bought it.

tomasss · 12-07-2020, 05:04 PM

Quote:

Originally Posted by Moyni

Yeah the book calls it a thermotimer

Weird...that part has nothing to do with time except it's a timebomb

what is the part #?

11-19-2020, 10:45 PM	#1
Moyni Board Member Join Date: Apr 2019 Location: Greensboro, NC	780 Bertone (PRV) Idling issue and some engine issues. Car is running super rich (see sparkplug image), has a funky idle where it seems fine in drive but when its in neutral / park it will surge the RPMs. Doesnt want to rev over 2500 without shaking like the space shuttle Columbia. I just did new spark plugs, wires, rotor and cap. Thinking try a new MAF and a fuel pressure regulator possibly. I also havent ruled out a vacuum leak. __________________ Classic Vehicle & Marketing Manager @ Hailey Import Service 2017 Alfa Romeo Giulia 1997 Volvo 960 Wagon 1987 Volvo 780 Bertone https://nordcarolina.com/

12-01-2020, 09:21 PM	#11
84B23F Board Member Join Date: Feb 2008 Location: Kansas, USA	Bosch LH-Jetronic 2.2 fuel injection....most likely then CTS Last edited by 84B23F; 12-01-2020 at 09:28 PM..

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11-22-2020, 12:42 PM	#2
JohnLane Board Member Join Date: Nov 2002 Location: Northern Washington	Pull the vacuum signal off of the fuel pressure regulator.... Fuel in that one? It may drip out or you may just smell it in the hose... Happens. Coolant temp sensor and/or wiring to it. Ohm meter across the CTS... Open = pig rich. Air mass meter much less likely; though everything about it is pretty old. Give her a set of fresh plugs too. I'm fond of Bosch H6DC. Check for vacuum leaks as doing so is good practice...Though a vacuum leak won't make her rich like this. __________________ Overkill is consistently more fun.

12-01-2020, 01:03 PM	#5
Moyni Board Member Join Date: Apr 2019 Location: Greensboro, NC	Anyone have a diagram of where the CTS would be? I have the Haynes manual as well as the Volvo Green manuals but still cant find it based off the online part numbers. This is the only sensor I have seen and I dont believe this is it

12-01-2020, 03:41 PM	#6
84B23F Board Member Join Date: Feb 2008 Location: Kansas, USA	Looks like a similar location for a 85-88 Pontiac Fiero...below the thermostat...either for the dash gauge, or for the ECU. Google for ECU sensor...and compare:=_

12-01-2020, 03:51 PM	#7
84B23F Board Member Join Date: Feb 2008 Location: Kansas, USA	Footnote - If your thermostat is open, it should be replaced...this could skew temp readings by ECU. Also, you most likely found the ECU's temp sensor...

12-01-2020, 04:51 PM	#9
Moyni Board Member Join Date: Apr 2019 Location: Greensboro, NC	So after talking with the bossman here in the shop, and doing some of our own research on the ol VIDA, it does seem like that is the sensor I need to replace. I am sort of firing the parts cannon at this motor in hopes of resolving this, however I still need to pull it back inside the shop on a slower day and take my time testing all the electrical components.

12-01-2020, 06:06 PM	#10
84B23F Board Member Join Date: Feb 2008 Location: Kansas, USA	RE: firing the parts cannon Replace coolant thermostat and coolant temperature sensor...Current CTS has been in there for "ages."

12-01-2020, 09:44 PM	#12
84B23F Board Member Join Date: Feb 2008 Location: Kansas, USA	Footnote - If there is a cold start injector, then that circuit/injector needs to be evaluated.

12-02-2020, 04:43 PM	#17
tomasss former PRVert Join Date: Oct 2008 Location: Leuven, Belgium	...are we discussing 780 or DeLerean here? I've replaced this temperature sensor on my PRV too so I remember it quite well.