Rough idle after MAF clean

Sorry, yes I took a plug out from each side, both looked fine as in light brown, no electrode damage/wear.

The revs do not rise any other time.

instead of gussing get the ecu fault read and if all is ok have the idle reset which you need a diagnostic kit to do

I need to get a Faultmate or some description. I see they are on eBay for £245 or so, but are they tied to the VIN?
Not sure if I am keeping this one for more than another year, may try to get a newer model (2000ish) in a year or so.
Anybody in South Wiltshire with one who I can pop over to?
If not, it would mean a trip to a mechanic and shell out £100 to just be told a code or two

Quick update:
Starting really well, wonderful in fact, 20 seconds later the idle drops.
Give it a rev for 20-30 seconds all is ok, drive to the end of the driveway, stall. Restart, all ok, drive off, very dead spot until the revs come up, then fine. Perfectly ok after that. I parked up 5 mins later and it idles really smoothly with no real pitch change at all. Driving off after that no dead spot at all, all is really well.
Just wish I could keep that smooth idle all the time.
Must be MAF related, the IACV was flithy and it idled well before I cleaned the MAF.
On idle tapping/knocking the MAF causes no change in speed.
I am hoping that the electrical cleaner I used on the MAF had just left a residue that carb cleaner and a cotton bud will remove.
Cheers

JamesBB said:

Quick update:
Starting really well, wonderful in fact, 20 seconds later the idle drops.
Give it a rev for 20-30 seconds all is ok, drive to the end of the driveway, stall. Restart, all ok, drive off, very dead spot until the revs come up, then fine. Perfectly ok after that. I parked up 5 mins later and it idles really smoothly with no real pitch change at all. Driving off after that no dead spot at all, all is really well.
Just wish I could keep that smooth idle all the time.
Must be MAF related, the IACV was flithy and it idled well before I cleaned the MAF.
On idle tapping/knocking the MAF causes no change in speed.
I am hoping that the electrical cleaner I used on the MAF had just left a residue that carb cleaner and a cotton bud will remove.
Cheers

Click to expand...

Reset those adaptive values before saying your MAF is bad.

I ran on LPG, when my adaptive values are way out it runs very bad on petrol.

Many people told me it's the MAF but it's not. When i reset the adaptive values and when i run only on petrol all is perfect...

A reset with testbook will cost much less than a OEM MAF (don't use ****part ones they don't work)

Stalled today on a roundabout.

At home I have tried unplugging the MAF, instantly stalls within a second of unplugging. Tapping around the MAF I understand can cause rev fluctuations if the MAF is faulty, but I do not get that either. IACV cleaned, it was dirty, but no real change.

On start up it needs a rev for a minute or so, not sure but seems to stabilise when the viscous fan eases off from starting.

I can see no blue arching etc when looking around the ignition leads in the dark.
Another thing I have noticed is the breather pipes from both rocker covers need to be replaced. The RHS is clear of blockage but just looks old and feel spongy, the LHS one is in a state, but is clear within the pipe itself, but it really needs to be changed as it is perishing and collapsing. I also checked the plastic oil separator as that was also flithy.

Since this only occured after cleaning the MAF, I am concerned that I may have found another fault.

I have 2 weeks warranty left on the car, it is one of those very basic warranties that covers limited items up to a grand. So it would be good to find out what is up and make a claim if possible.

Wanted to get a Faultmate, then saw the post on RSW's pending offering, but may need to get this hooked up to something prior to the warrantly expiration in case it is something I can claim.

Yours, worried.......

JamesBB said:

......the LHS one is in a state, but is clear within the pipe itself, but it really needs to be changed as it is perishing and collapsing.....

Click to expand...

Could this be cracked and letting air into the inlet system thus upsetting the mixture?

Pete

Happy new year all.

An update on the saga..........

I plan to hook a voltmeter to the MAF output tomorrow, but I am wondering if the IAC valve can/should be adjusted? See this link:
http://www.landyzone.co.uk/lz/f10/p38-4-6-base-idle-setting-87070.html
Page 400 on RAVE - Service repair no - 19.22.13 suggests that also.

I cleaned the valve again, checked all the leads looked ok and not resting on bare metal anywhere, lowering the risk of a bad spark. Lucas leads, I have read these are rubbish?

Latest situation is:

Start (instantly no probs everytime), it revs to about 1100 rpm then drops to 700-800 rpm (no apparent missing) then drops to stall (everytime) runs for 5-8 seconds.
Start again, the same, unless I give the gas pedal a little press, then it revs up to 1500-2000 rpm, cycles down to near stall, then again (with no extra pressure on the gas) revs again to 1500-2000 rpm, then back down the whole time it sounds like it is missing. This cycle happens for about 30 seconds or so (or until the missing stops) and I can leave the gas alone and it idles well, albeit slow 500-600 rpm.

Any thoughts most welcome to help me save some funds and while I try to find a local workshop capable........

JamesBB said:

Happy new year all.

An update on the saga..........

I plan to hook a voltmeter to the MAF output tomorrow, but I am wondering if the IAC valve can/should be adjusted? See this link:
http://www.landyzone.co.uk/lz/f10/p38-4-6-base-idle-setting-87070.html
Page 400 on RAVE - Service repair no - 19.22.13 suggests that also.

I cleaned the valve again, checked all the leads looked ok and not resting on bare metal anywhere, lowering the risk of a bad spark. Lucas leads, I have read these are rubbish?

Latest situation is:

Start (instantly no probs everytime), it revs to about 1100 rpm then drops to 700-800 rpm (no apparent missing) then drops to stall (everytime) runs for 5-8 seconds.
Start again, the same, unless I give the gas pedal a little press, then it revs up to 1500-2000 rpm, cycles down to near stall, then again (with no extra pressure on the gas) revs again to 1500-2000 rpm, then back down the whole time it sounds like it is missing. This cycle happens for about 30 seconds or so (or until the missing stops) and I can leave the gas alone and it idles well, albeit slow 500-600 rpm.

Any thoughts most welcome to help me save some funds and while I try to find a local workshop capable........

Click to expand...

Looks like your describing my car behaviour when it's fuel trims are way out of limit.

Go to a Testbook and reset your adaptive values, you'll have a lot of infos and resetted fuel trims.

996TURBO said:

Looks like your describing my car behaviour when it's fuel trims are way out of limit.

Go to a Testbook and reset your adaptive values, you'll have a lot of infos and resetted fuel trims.

Click to expand...

Think he was told that in fifth post. The question would seem to be. "Why you no rissen Glasshopper".

Sorry guys, I know I need to reset the adaptive values, I was delaying it based on the options of buying a Faultmate or similar.

As it was so cold and attempting to snow today, I did nothing. Tomorrow I will call the dealer I got it from and see if they will do it for me. I need to get the security codes from them anyway........

Cheers

Was the car supplied by a Land Rover specialist? I only ask because if not, I'd say it's unlikely they'll have the right gear to interogate your ECM, unless they specialise/ advertise a diagnostics service.
There must be someone on here in the area that is willing to read your fault codes and reset the long-term fuel map?
As a guide, my local diagnostics chap charges £30 for a 'scan' and has dealt with a fair amount of P38's. Kent is a little too far away from you though!

David_Cooper said:

Was the car supplied by a Land Rover specialist? I only ask because if not, I'd say it's unlikely they'll have the right gear to interogate your ECM, unless they specialise/ advertise a diagnostics service.
There must be someone on here in the area that is willing to read your fault codes and reset the long-term fuel map?
As a guide, my local diagnostics chap charges £30 for a 'scan' and has dealt with a fair amount of P38's. Kent is a little too far away from you though!

Click to expand...

Agggggggh, I was in Kent over Christmas too. :doh:
I visit family down there often(ish).

The car came from the main Land Rover dealership in my area, so fingers crossed I can convince them to reset it as it was only bought 2.5 months ago, if not I have find somebody cheaper in the area. Let you know how it goes.

JamesBB said:

Agggggggh, I was in Kent over Christmas too. :doh:
I visit family down there often(ish).

The car came from the main Land Rover dealership in my area, so fingers crossed I can convince them to reset it as it was only bought 2.5 months ago, if not I have find somebody cheaper in the area. Let you know how it goes.

Click to expand...

I would not tell them you have been playing with it if i were you.

Yeah Wammers is correct in that it may be best not to reveal anything that could mean they can wriggle out of any warranty...
It's annoying really because resetting the fuel trims is literally a two-minute job. Mind you, a reset of the codes and a quick check of the live readings would be lovely.. but probably asking too much !
Have a tactfull word with a friendly tech there?

It does sound like a fuelling issue. Either trims (here's an idea, get them reset!). I had a similar symptom which went away when I replaced the fuel filter. I suspect my in-tank fuel pump is a little weak too because it still sometimes does it if the fuel gets too low. So that'll be something to look at in the near future.

Quick update, annoyingly they said the P38s use a closed system, there are no fuel trims to reset.
However they are going to give me a 1 hour free diag session next week.

Just bumped this back up as I was wondering if James ever got the problem sorted. Did resetting the adaptive values cure it?

My mechanic mate has been looking at my '99 P38 as when cold it runs like a bag of spanners - coughing splutting with revs dropping, stalling, etc for about 5 - 10 mins until warmed up. When warm, it's fine.

I did post the other day and Wammers suggested checking/cleaning the idle air control valve which we did. No change. We got a MAF sensor fault on diagnostic, borrowed another MAF and it worked lovely. However, I've just bought a new MAF and it hasn't solved it. It's still ****e!

There is the remote possibility that the replacement part is fault but unlikely. Could the problem be wiring to the MAF or does anyone have any other suggestions?

JamesBB said:

Quick update, annoyingly they said the P38s use a closed system, there are no fuel trims to reset.
However they are going to give me a 1 hour free diag session next week.

Click to expand...

They don't know their job well. Testbook permits reset of adaptive fuel trims. I do it every 6 months.

Topboy said:

Just bumped this back up as I was wondering if James ever got the problem sorted. Did resetting the adaptive values cure it?

My mechanic mate has been looking at my '99 P38 as when cold it runs like a bag of spanners - coughing splutting with revs dropping, stalling, etc for about 5 - 10 mins until warmed up. When warm, it's fine.

I did post the other day and Wammers suggested checking/cleaning the idle air control valve which we did. No change. We got a MAF sensor fault on diagnostic, borrowed another MAF and it worked lovely. However, I've just bought a new MAF and it hasn't solved it. It's still ****e!

There is the remote possibility that the replacement part is fault but unlikely. Could the problem be wiring to the MAF or does anyone have any other suggestions?

Click to expand...

Did you buy a ****part MAF or a Genuine (4to 6 times more expensive)?