Yet more engine issues

All the information you need on engine-problems is here. The engine includes the Turbo-charger, airco and everything else you'll find under the bonnet.

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gsa60
Started learning about 480
Posts: 96
Joined: Tue May 21, 2013 10:18 pm

Yet more engine issues

Post by gsa60 » Tue Jan 21, 2020 6:55 pm

Hi friends,
having sorted the missfiring issues due to a bad distributor isolation, I have been driving for almost an year an almost perfect engine.
But from last few weeks I am having yet more issues.
This happens mostly on low engine speed and moderate trhottle application: the car as massive flat spots and almost stalls.
Going uphill withbpassengers is a nightmare, I have to keep revs high and not pass a quarter throttle.
On intersections if I do a brisk acceleretion from neutral, it almost dies. I have to be well over 2000rpm an very slowly release the clutch.
At high RPM and wide open throttle it still happens noticeably


Already tried:
Checking leaks (at least in the easiest spots)
Swapping MAFs
Disconnected MAF for a test drive with zero difference
Swapping ecu (robou and standard)

Other back ground
Idles perfectly, coast perfectly
Fuel filter replaced around two years.
Injectors cleaned a year ago.

Any Idea?
I an starting to get fed up. One thing gets fixed and then another appens.

jifflemon
480 Is my middle name
Posts: 2464
Joined: Sat Dec 17, 2016 11:03 am

Re: Yet more engine issues

Post by jifflemon » Wed Jan 22, 2020 8:11 am

So, as you mentioned a Robou ECU, I'm presuming you're turbo?

Does it boost ok?
Did it start suddenly or has it been gradually getting worse?
Any changes done prior to it starting?
Does it idle correctly?

gsa60
Started learning about 480
Posts: 96
Joined: Tue May 21, 2013 10:18 pm

Re: Yet more engine issues

Post by gsa60 » Wed Jan 22, 2020 1:00 pm

Hi, yeah I forgot its a 91 turbo.

Idles perfectly.
I noticed it about two weeks ago. I think when it appeared, it appeared full on. Perhaps getting a bit worse now.

BR

Robou
Knows an Aerodeck isn't a 480
Posts: 270
Joined: Sun Jul 08, 2007 11:34 pm

Re: Yet more engine issues

Post by Robou » Wed Jan 22, 2020 10:47 pm

Perform a reset on the roboumod and check if the problem is right there from the beginning. Both ECUs may be in some loop as a result of turbo spikes or some ignition anomaly. Also check the vacuum in the air pipe to the ECU. This is no cure but it may give a direction of where to find a solution.
Too old to bother
480 Turbo midst '91

gsa60
Started learning about 480
Posts: 96
Joined: Tue May 21, 2013 10:18 pm

Re: Yet more engine issues

Post by gsa60 » Thu Jan 23, 2020 10:15 am

Hi thanks for the help.
I Did a reset via the jumpers for 30 seconds (engine hot). Problem was there from the start.
I then umpluged the pipe conecting to the ecu. I could feel good vacuum. I also could feel bost (I drove a bit with the pipe unconnected).
While driving, it stuttered so bad that the 3rd gear got disengaged at WOT around 3000RPM.
Not sure what is happening

cranna21
Can tell where the 480 was built
Posts: 313
Joined: Sat Jan 11, 2014 3:44 pm
Location: Aberdeenshire, Huntly

Re: Yet more engine issues

Post by cranna21 » Thu Jan 23, 2020 10:23 am

Might be an odd suggestion or maybe something you've checked, is the air filter still in ok condition? not totally choked up? or at the other end of the spectrum doesn't have a massive hole in it?

the other thing that crossed my mind is a dying fuel pump/blocked gauze on the fuel pump pick up

Another thing to check would be the crank sensor and all its associated wiring, the signal can be susceptible to interference from other frequencies if the earth for the sensor is dodgy and for that reason, you could be randomly losing crank signal and therefor randomly losing spark.

Just spitballing idea's, might have already checked these things but you never know :)
'91 480 ES 2.0l 16v 'Williams' Conversion - 212bhp/230nm
'90 940 GL 2.0l Estate
'08 XC90 D5 SE Premium

gsa60
Started learning about 480
Posts: 96
Joined: Tue May 21, 2013 10:18 pm

Re: Yet more engine issues

Post by gsa60 » Sat Jan 25, 2020 9:35 pm

Guys, one more question. If it is air or vacum leak related, wouldn't disconnect the maf make itba bit better. At least for low revs?

gsa60
Started learning about 480
Posts: 96
Joined: Tue May 21, 2013 10:18 pm

Re: Yet more engine issues

Post by gsa60 » Sun Jan 26, 2020 6:00 pm

So, this weekend I started my teardow.
I disconnected all pipework form the maf till the manifold (included) all pipes were ok even the ones that attach to the turbo.
The throttle body was rather oily, as well as the TPS sensor. The oil came from the cranckcase breeder valve. This, because the trhottle body had oil on the engine side, the intake one was clean. Also regarding the 4 manifold pipes that connect to the engine, they were oil free.

Rotor and spark related stuf were ok.

The only thing that I think was bad was the fuel pressure regulator valve. I connected a pipe to the return side, and at idle it did not let any fuel return. Is this supposed to work that way?
Is there any way to test it?
Can it be the cause of the issue?
I was trying to look for some replacement but am not able to find any.
Does anyone know where to get one?
Thanks

Robou
Knows an Aerodeck isn't a 480
Posts: 270
Joined: Sun Jul 08, 2007 11:34 pm

Re: Yet more engine issues

Post by Robou » Sun Jan 26, 2020 10:23 pm

You found the culprit, I suppose. Start by replacing the filter, no harm done anyway. If still no return the pump should be checked.
Too old to bother
480 Turbo midst '91

gsa60
Started learning about 480
Posts: 96
Joined: Tue May 21, 2013 10:18 pm

Re: Yet more engine issues

Post by gsa60 » Mon Jan 27, 2020 8:43 am

Thanks for the help.
I'll try to source one.
Oh and btw I also disconnected the line that comes from the pump and connects to the injector rail (on the 4th cylinder side) when crancking, a good anount of fuel came out.
BR

Alan 480
480 Is my middle name
Posts: 1489
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Location: Aberdeen

Re: Yet more engine issues

Post by Alan 480 » Mon Jan 27, 2020 12:33 pm

gsa60 wrote:
Mon Jan 27, 2020 8:43 am
Thanks for the help.
I'll try to source one.
Oh and btw I also disconnected the line that comes from the pump and connects to the injector rail (on the 4th cylinder side) when crancking, a good anount of fuel came out.
BR
HBOL gives volume per minute from each injector type , useful as a starting point if not enough fuel???
Alan

480 ES 2litre 'Celebration' ? , C30 1.8ES, SS1

gsa60
Started learning about 480
Posts: 96
Joined: Tue May 21, 2013 10:18 pm

Re: Yet more engine issues

Post by gsa60 » Mon Mar 02, 2020 8:53 pm

Hi friends,
Unfortunately the regulator did not solve the issue.
Took it also to volvo dealer but without success.
If I ever find the cause, I'll keep you posted.
Cheers

gsa60
Started learning about 480
Posts: 96
Joined: Tue May 21, 2013 10:18 pm

Re: Yet more engine issues

Post by gsa60 » Tue Jun 16, 2020 8:28 am

Hi everyone,
I was being dumb. I did not understood that the pump was at fault as you sugested.
I replaced it and no more issues.
Thank you very much for the help.

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