A few 951 issues from new member...

[DonLogan]

Hi All,

I'm a long time lurker of this and other 944 forums and I've reached the point where I'd like some direct advice and hopefully confirmation of what I've read here and there from you knowledgable folks.

In case I've not set my signature right, I've got a 1986 RHD Euro spec 951 (as I live in the UK). It's standard apart from a manual boost enhancer and 3 bar FPR. It also had a recent top end rebuild (1500ish miles ago) after a broken tensioner bolt allowed the timing to make up it's own beat, bending a few valves in the process

Anyway, my queries for today are:-

1. The oil pressure gauge likes to intermittantly peg itself above 5 bar. It will act 'normally' with the oil light on and the needle at zero with the ignition on and rise to 5 bar shortly after starting. It will then stay there until the engine has warmed and then drop to 2-3 at idle ith a warm engine rising to 4-4.5 bar as engine load increases. Then it 'decides' to peg itself way above 5 bar and will stick there.

I've read on oil pressure gauge posts that I should check the ground locations, some of which are easy to find and some which have so far eluded me. Please can someone advise the likely ground or short locations I should be checking? (I have a copy of Technoducks ground diagram) I'm also thinking that if these are proved OK, I should look to replace the oil pressure gauge sender?

2. Regarding the 3 bar FPR - This was an addition I made when I suspected the original FPR was bad (noisy fuel pump, lumpy idle, slight hesitation to increase revs). I was going to replace it with a stock 2.5 FPR but was pointed towards the 3 bar FPR by a parts website and as it was the same price as stock, I installed it. It certainly made a difference with the fuel pump noise back to normal levels, a more solid idle and rev hesitation is gone. However, my fuel economy has suffered terribly and reading posts here, I'm suspecting this FPR could be the main suspect due to running rich along with the obvious vacuum leak I discovered on the weekend on one of the t-pieces, which is split. I'm thinking that as I'm running almost stock the standard 2.5 FPR would suffice and improve economy. Should I also look at the the fuel damper? Any other thoughts on this one?

3. Lumpy idle is back since being improved by the new FPR. It never stalls but sometimes feels like it will and will 'hunt' around 600-1100 rpm before settling at about 800 rpm after some time. Is that likely somewhat caused by the vacuum leak and possible dodgy grounds that may or may not be contributing to the oil pressure sender problem? Should I suspect the idle stabiliser valve?

Thanks in advance for any help.

Don

[kdjones2000]

Don,

Firstly welcome to the forum officially!

Regarding your questions, here are some guesses/inputs to think about.

1) Since you had the head off for the valve work, did the wires in the front of the head get pinched at all? You might be having the oil pressure wire going to the sending unit shorting out when the engine gets hot, giving you the pegged needle.

2) Go back to a 2.5 Bar FPR. Your EEPROM has fuel maps that are calibrated for 2.5Bar, not 3.0Bar. You are therefore running rich most if not all of the time.

3) When my FPR died, the Damper was not far behind. I would change it out as well and see if that helps your idle. Your O2 sensor is also old and may need replacement, especially if you have been dumping a rich mixture at it with that 3.0 Bar FPR.

Good luck,
Keith

[DonLogan]

Thanks Keith.

I like your thinking behind the oil pressure gauge pegging as it only starts playing up once the engine is warm, so I'll have a look at the wiring. The sender is above the oil filter right? Follow the wires looking and feeling for anything odd.

I'll look around for a new standard FPR and damper. Where exactly is the O2 sensor?

Cheers,

Don

[Techno Duck]

I would check for loose or shorted wiring for the oil pressure sender. Otherwise i would just replace the sender as they do stuff like you mentioned when they go bad.

Putting a new 2.5bar regulator and fixing any of the vacuum leaks you find will probably fix most of your issues. Regarding the o2 sensor, im not sure if your car even has one as its a ROW model. However if you do, the sensor itself is located in the crossover uppipe, about 3-4 inches from the hotside of the turbo. There will be a 3-pin black round barrel connector mounted to the bracket for the speed / ref sensors on the back of the intake manifold (inbetween firewall and intake), that is for the o2 sensor.

[DonLogan]

Thanks Techno Duck,

I'll hopefully have time this weekend to look at the oil sender wiring and vacuum leaks and with luck the regulator and damper I'm about to order will be here in time too.

I'll also look for the O2 sensor but suspect, as you say, that it doesn't have one being a ROW model.


Cheers,

Don

[DonLogan]

Thought I'd best update this thread with recent developments...

After checking the wiring as much as possible and the earths, I replaced the oil pressure sender. Now all good again with normal readings.

The leaking vacuum t-piece has so far been bodged up with insulation tape which seems to have improved the idle some. I'll be replacing it with a new one soon.

Having clocked up just over 2000 miles since the rebuild, I booked it into the garage for the belts to be re-tensioned and asked them to look into the running rich issue. On collection I was advised that it was running fine once warmed up and the co/idle had been reset. So I've not done anything regarding the 3.0 bar FPR for now. It's still under scrutiny though and I'm going to check the ECU for standard or uprated chips. I'd assumed it was standard but it came with a passive boost enhancer and I know they are sometimes done with new chips.

Anyway for now, it's running better than before and I can see the oil pressure which gives some piece of mind too!

Next up is investigating the sunroof which mysteriously stopped working after going in for the re-tension and a good spring clean.

Cheers,
Don