TD5 misfire @ 2700-3000 RPM

Hi all

I wonder if someone might be able to help I have a 2003 td5 , no egr valve

It has a very annoying misfire around 2700rpm , if i stick it in park and slowly increase the revs , its smooth up until 2700 rpm then it will hunt around from about 2700rpm to 3000rpm, any higher or lower and its smooth, if i let the revs increase slowly past 3000 to say 3300 and let my foot off there is kind of a missfire and the car rocks a little

It does this most of the time but not always.

The fuel regulator was replaced about 1k miles ago.

I have unplugged the MAF and tried with that not plugged in and the same thing happened.

Injector loom is only a couple of years old.

My local landy man cant get on it for two weeks so i wondered if anyone might be able to shed some light on it please


thanks

check this out www.discovery2.co.uk / Waste Gate Modulator - Over boosting , you can check it before buying a new one by taking the pipe from the modulator's bottom and make somehow to connect it directly to the turbo wastegate valve, if it will run fine that way it means the modulator is fubar'd...also check fuse F2 in engine bay to rule it out too

thanks for taking the time to reply much appreciated.

Its taken me a bit of time to get some time with the local landy guy.

We have tried a new MAF and new throttle & sensor , still the same , the boost pressure shows on the computer when driving seems to be pretty consistent and doesnt read any over boosting although its a bit down he rekons.

We check fuel pressure and its just over 4 bar from the pump.

Thinking injector seals next , any thoughts ?

cheers

tim

timmyp666 said:

thanks for taking the time to reply much appreciated.

Its taken me a bit of time to get some time with the local landy guy.

We have tried a new MAF and new throttle & sensor , still the same , the boost pressure shows on the computer when driving seems to be pretty consistent and doesnt read any over boosting although its a bit down he rekons.

We check fuel pressure and its just over 4 bar from the pump.

Thinking injector seals next , any thoughts ?

cheers

tim

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Hi Tim, it could be the Wastegate Modulator misbehaving. This device cuts the turbo if the ECU senses any danger.

Also check/clean the MAP (Manifold Absolute Pressure) sensor in the inlet manifold.


Dave

if all these are ruled out make sure that the turbo/intercooler hoses are not delaminated(soft) and the CAT if it's still on might be clogged as well... but did you bypass the wastegate modulator as i said?, the fact that you have boost reading doesnt mean that the wastegate modulator works well

Thanks , guys , i kinda assumed if the boost pressure was consistent it wouldnt be those , but defo worth a check.

Whats the best way to check the CAT ?

Shes booked in for the seals to be done on tuesday , so i will give these a go at the weekend before she goes in.

shes needs a new gearbox really so I am trying to get all the niggles ironed out first to see if its worth keeping or just binning.

Thanks again for the help much appreciated

IMO the injector seals would give different symptoms, undo the downpipe from the turbo and go for a ride this way, it will be a bit noisy but i don't see other way to rule this out...also there's a strainer under the FPR which used to be clogged and give missfire at high revs... i presumeyou checked to not be oil in the ECU red plug... if not and there is oil get a new injector loom too

Thanks , I replaced the injector loom about 15k miles ago so to be honest I ruled that out but having had two FPRs in the last 18 months i shouldn't rule anything out !

I will give that a go at the weekend as well.

Thanks again for taking the time to reply much appreciated.

if you didnt check the filter under the FPR when you replaced it you better do it cos if it's cloged it could be the reason for the FPR to fail as it's diaphragm is forced by the backpressure

injector seals were all shot apparently , shes running super smooth now !

Thanks for all the quick replies much appreciated guys

Guys read through this forum an yous have helped me solve my surging problem , tried 2 brand new (aftermarket) MAF sensors , problem went away when unplugged the second one but this identified there was an underlying issue. Cleaned the MAP sensor , still surging , tested the resistance on the new MAF proved it was doing its job still surged.

Pointed towards the waste gate control valve , changed it out and it seems tobehaving itself for now

Thanks again

The fault came back again . Turns out it was a faulty waste gate on the turbo . Problem now solved , I hope

luminox said:

The fault came back again . Turns out it was a faulty waste gate on the turbo . Problem now solved , I hope

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Did you just replace the wastegate for a new one or did you troubleshoot it in some way first?