HGT Exhuast Oxygen Sensor problem?????

[Phil Charman]

Hi guys........

Recently I been having a bit of trouble with my lovely HGT in the mornings...

I start her up in in the morning & if I move within the first minute, it missfires constantly, literally for about 1 minute! Then it starts to run normally.

The only other time I notice this irritating problem is if I put my foot down, it can hesitate then also. So I changed my plugs to top range plugs, replaced my Coil packs as well, but unfortunately the problem remains!!

So I had Angel Tuning out today to do a diagnostic test on it, turns out it might be the exhaust oxygen sensor or the lamber sensor, or it could be the control module for either!!

So basically its throwing out my air & fuel mixture on start up hence the missfire.

Anyone else had this problem & do you know if its expensive to sort?

 

[Von]

This is exactly what happens to my HGT. I have a complete hash of an air filter on it at the moment though (put on before I got the car a few weeks ago). I am going to fit a replacement before I look for anything else. Next call will be the lambda sesnsor if that doesn't work.

Good luck and let me know if you sort it!

Von

 

[Sven]

If you have flat spots when accelerating from a stand still, the lambda is shot. A new one costs around 40 quid.
In general, the lambda should be changed every 80 000km.

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[J]

A common mistake is because the ECU say lambda people replace the lambda. This is not always the real cause of the problem but the symptom. If something else is wrong mechanical/electrical it can throw the lambda out of range thus giving a lambda fault but not necessarily the lambda that is at fault. I would investigate further before replacing any parts. Test the lambda is being heated from cold. Also test coolant temp sensor and consider AFM worse case. It may well be the lambda but do some more tests first as it only costs you time (if you can do it yourself).

 

[J]

Lambda is the only component that gives feedback to the ECU about combustion so when there is a lambda fault it could mean that there is something wrong with combustion and not the sensor.

For example if the fuel pressure regulator is broken and the pressure should be 3BAR but now is 4.5Bar the car is going to run rich. The lambda will pick this up and try to run leaner but its out of range so the ECU will give a lambda fault. People will replace the lambda and then five minutes later the fault is back again, when the real problem is the FPR. Always take lambda faults as a pinch of salt.

 

[Phil Charman]

Hi guys,

Thanks for your responses, yes Angel Tuning did say it might not be the Lambda sensor, it could be the actual control unit as well, it could be pre Cat or Post Cat sensors throwing out the mixture, but it would be nice if it was something as simple as replacing the lambda sensor.

Next step is I have booked it in to have the control unit & lambda sensor looked at & poss replaced.

But yes I do have flat spots when accelerating, & it would seem something has to wait to be warmed up before the engine runs normally.

Cheers Guys, i´ll keep you posted

 

[nico]

please do phil cos i'm experiencing this intermittantly with my other motor and the garage reckon the maf but I don't think so.

 

[Tom]

The lambda sensor only works when the engine is warm. Sounds like something else is the cause.

 

[nico]

mystery goes on....

Could perhaps even be two faults on phils then as mines ok cold but flat spots when warm. My clutch release bearings wearing so I had wondered whther that could be contributing but I doubt it.

Reading archive posts and speaking to garage, I thought at first it was Fuel pressure regulator, then garge said no - was more likely MAF.

Since I've hada LPG conversion done this must rule out the pressure regulator cos I get the flat spots running on unleaded & LPG (which I'm guessing have differetn regulators).

 

[Philip]

HGT Sensor Problem

Been speaking to various people about this problem now, a good friend of mine said he has had this problem with one of his mates HGT's before & said he's 90% sure that its the MAF sensor, so I've booked it in to have it replaced along with the Lambda as well. I hope this cures the problem. My poor beloved HGT doesn't like waking up!

I'll let you know what happens once they have been replaced.

Phil

 

[Von]

Hi all

As posted earlier I was experiencing similar problems. Car went completely stupid whilst attempting to get to the Karting at the weekend. On advice from Tommy, disconnected the MAF. Wow, HGT has turned from a stuttering pussycat into a hooligan, fantastic. New MAF on the way, am using far too much juice without it connected. Other half, whose job is electronics, recons he can fix the old MAF as the manuel we downloaded has a curcuit diagram. Will let you know, but if he can it may be worth holding on to any dead MAF sensors as they may be fixable.

Von

PS Edited three times as I have forgotten how to spell!!!!!

 

[Philip]

Hi Von,

thats interesting about disconnecting the MAF, didn't realise you could do that. I thought if you disconnected it, it would run worse than it does now. I might try it later on, but dont you need a torx set to take it off? Looked at the screws before, sure thats what they are.

Cheers Von, still think I might have the original replaced, any idea how much they retail at?

Phil

 

[Von]

Think he just unplugged it, not sure didn't take him long. The only problem with it unplugged is very low revs when pulling away, have to feather the clutch etc. and much reduced fuel consumption. I looked on various sites and they seemed to be about £100+. Good luck.

Von

 

[nico]

I seem to remember in past thread, that the MAFD fails due to debris from the air accumulating on a wire through which current is passed to determine the air temp etc. Can anyone confirm if indeed this is where the fault usually lies with MAF's, and if so - is the quality of the air filter at all a factor?? I recall the thread also mentioning that this electrical thread could possibly be be cleaned to restore full function!?

 

[Phil Charman]

Well I will be taking out my MAF in next few days to replace it with a new one, so it will be interesting to see if it is all clogged up inside. It would explain why there might be flats spots.

I disconnect the MAF yesterday to see what the difference once, power gains are impressive, just goes to show how much power that silly sensor holds back!

Will let you know once replaced.

Phil