Any Ideas

[ZTec]

Hi All,

I’ve noticed recently that I’m getting a strong smell of fuel with the exhaust gasses, MPG is down to 31, any ideas?
Thanks

 

[t-tony]

Check all the intake rubber hoses and vacc. pipes etc. Remove fuel cap (slowly) to see if there's any pressure in the tank.

Tony.

 

[ZTec]

Check all the intake rubber hoses and vacc. pipes etc. Remove fuel cap (slowly) to see if there's any pressure in the tank.

Tony.

Hi Tony, I’ve checked the ones I know about - the ribbed one coming from the filter box and the one branching off it on the right. No pressure in the tank when I undo the cap.

 

[t-tony]

Has the idle speed gotten higher than usual? Thats a good indicator of an air leak.

Tony.

 

[ZTec]

Has the idle speed gotten higher than usual? Thats a good indicator of an air leak.

Tony.

Not noticeable, around 1000rpm maybe a tad higher when I come to a standstill then after a few seconds drops to around 800rpm.

 

[Lee]

The fuel filter is under a plastic cover under the car, It sits below the passenger seat. They have a small rubber 1" connection each end to make install easier, make sure its not weeping round there. Also make sure the fuel filler housing neck is not blocked, could be fuel sitting in the neck area below the nozzle.

 

[Rudyrov]

You could check the O2 sensors, as they get old they ma not work quite right and not adjust fuel mix properly.

 

[ZTec]

You could check the O2 sensors, as they get old they ma not work quite right and not adjust fuel mix properly.

Would that show up with a diagnostic tool?

 

[ZTec]

I’ll have a look, thanks Lee.

The fuel filter is under a plastic cover under the car, It sits below the passenger seat. They have a small rubber 1" connection each end to make install easier, make sure its not weeping round there. Also make sure the fuel filler housing neck is not blocked, could be fuel sitting in the neck area below the nozzle.

 

[colb]

If you have diagnostics that shows live data you can watch what the lambda sensor(s) are doing, you should see the voltage cycling with the engine running, its a good indication on how they are performing they do get a bit slow as they age.

 

[ZTec]

If you have diagnostics that shows live data you can watch what the lambda sensor(s) are doing, you should see the voltage cycling with the engine running, its a good indication on how they are performing they do get a bit slow as they age.

Unfortunately I don’t have access to such diagnostic equipment, but thanks anyway for the info

 

[colb]

If your out and about pay me a visit or we could meet up somewhere and I will plug my diagnostics in.
PM me for details.

 

[colb]

Checked it out this afternoon old codes present using INPA showed 108 which relates to an interuption of power (Battery disconnected)
Second old code present 148 Leitungsfehler (Line fault)
Looks like these were connected with each other and wouldn't be a cause for misfueling making it run rich.

Had a look at what the Lambda sensors were doing Pre Cat was ranging up and down with voltage and looked to be functioning ok.
Post cat sensor was static at mid point on the scale, didn't move at all so looks like this may be at fault.

Checked on OEM and car should have pre and post cat sensors, couldn't explore more this afternoon but it has come up with something to investigate further. The rich running is noticable from the exhaust smell.

Maf didnt seem to be performing very well could do with investigating further. Advised to disconnect it and see how the default settings it will revert to makes any difference.

New exhaust to be fitted soon so might be prudent to replace the post cat sensor at the same time.

 

[ZTec]

Checked it out this afternoon old codes present using INPA showed 108 which relates to an interuption of power (Battery disconnected)
Second old code present 148 Leitungsfehler (Line fault)
Looks like these were connected with each other and wouldn't be a cause for misfueling making it run rich.

Had a look at what the Lambda sensors were doing Pre Cat was ranging up and down with voltage and looked to be functioning ok.
Post cat sensor was static at mid point on the scale, didn't move at all so looks like this may be at fault.

Checked on OEM and car should have pre and post cat sensors, couldn't explore more this afternoon but it has come up with something to investigate further. The rich running is noticable from the exhaust smell.

Maf didnt seem to be performing very well could do with investigating further. Advised to disconnect it and see how the default settings it will revert to makes any difference.

New exhaust to be fitted soon so might be prudent to replace the post cat sensor at the same time.

Hi Colin, many thanks again for taking time out to check out my car.
The two codes the INPA threw up 108 & 148 as you mentioned don’t seem to be related to the actual problem.
My first port of call tomorrow is to get under the car and check the connection to the post cat sensor and take it from there and give the MAF a clean.

 

[ZTec]

Just been on real OEM and the post cat O2 sensor on the diagram is greyed out???

 

[colb]

Just had another look on OEM and yes its greyed out so maybe you don't have a post cat sensor, best get under there and check visually to confirm. If there isn't one then maybe thats why we were seeing a flat line on the monitor.
Pre cat one seemed to be ranging ok when viewed in INPA, didnt look slow.
Be careful cleaning the Maf, I tried that and it killed it completly, new one sorted my problem.
Bad Mafs don't always set codes in my experience and if its not performing as it should it will have an effect on the fueling.
Disconnect it and see if the default it will go to leans the mixture. Might be worth pulling the spark plugs to have a look at the colour they are, should be a bit black if running too rich.

 

[ZTec]

Just had another look on OEM and yes its greyed out so maybe you don't have a post cat sensor, best get under there and check visually to confirm. If there isn't one then maybe thats why we were seeing a flat line on the monitor.
Pre cat one seemed to be ranging ok when viewed in INPA, didnt look slow.
Be careful cleaning the Maf, I tried that and it killed it completly, new one sorted my problem.
Bad Mafs don't always set codes in my experience and if its not performing as it should it will have an effect on the fueling.
Disconnect it and see if the default it will go to leans the mixture. Might be worth pulling the spark plugs to have a look at the colour they are, should be a bit black if running too rich.

I’ll get under it in the morning and have a look, then disconnect the MAF and see how she runs and I’ll report back to you.

 

[ZTec]

Been under the car and the post cat O2 sensor is not fitted to the M44 as per the real OEM diagram, just has the pre cat sensor fitted.

Next the MAF, started the car and let it warm up. Disconnected the MAF, there was a slight blip in revs which settled immediately, revved the car, seemed fine then reconnected the MAF, no change in revs.
Million dollar question, is it the MAF, don’t know myself as I wasn’t sure what to expect on disconnecting and reconnecting. Next step is to remove the MAF clean and try again. Cannot load video as file is too large.

 

[colb]

At least we know there is only pre cat sensor for sure now hence the flat line for it in INPA.
Drive the car with Maf disconnected to see if default settings make any difference.
The fact that the Maf didn't show much activity in live data might be an indication that it isn't working as it should. Live Diagnostics should show it consuming gals per second when revs rise looked a bit low when we looked at it yesterday. Could do with swapping a known good one in to see if that changes things before shelling out on an OEM part.

 

[gookah]

take the car for a run with the MAF disconnected, and see what the performance is like. Mine was different again. One replacement MAF later and all was good.