OBD2 converted 2.9 Corrado - Feels down on power

[EnthusiastOwned 7]

Hey you guys!

I have a 2.9 VR6 OBD2 converted Corrado. It's been converted quite some time now and the car was perfect for the first 12 months after the conversion and went like stink.

Recently it has felt down on power with flat spots and the exhaust note is noticeably quiter. The revs on idle sometimes fluctuate.

No Errors on Vagcom.

I've tried a replacement cam sensor, MAF and IAT sensor. No vac leaks as far as I can see.

The Coilpack, HT leads and plugs are brand new.

What should I be looking at next?

Edited February 15, 2014 by EnthusiastOwned

[cactusjackslade 146]

Incorrect air fuel mixture from lambda sensor is a poss.. Doesn't always bring up fault codes...

[EnthusiastOwned 7]

Incorrect air fuel mixture from lambda sensor is a poss.. Doesn't always bring up fault codes...

Could be a possibility. Any way I can check the readings using Vagcom?

Any idea how much the genuine vag ones are anyone?

[VR6Pete 1,455]

Have you had it on rollers? Mine was only pushing out 194bhp but think its because of my head issues! Did you swap for the obd2 lambda?

Club Chairman

[EnthusiastOwned 7]

Yeah, swapped everything.

The car pulled like a train after the OBD2 conversion so I know that I did it right. This has occurred 12 months later.

All wiring is good and has been checked recently.

Not had it on the rollers. What head issues did you have?

[leespiro 9]

yeh when i converted my golf from odb1 to 2 the exhaust note was quieter and the air filter roar i noticed that the throttle body size was smaller on the odb2 than the 1

[EnthusiastOwned 7]

yeh when i converted my golf from odb1 to 2 the exhaust note was quieter and the air filter roar i noticed that the throttle body size was smaller on the odb2 than the 1

Mine sounded quieter / more refined after the OBD2 conversion. But it's gone even quieter since the suspected power loss.

I don't think this issue is related to the conversion itself.

[VR6Pete 1,455]

I'm down on power and misfire top end, currently at stealth having new head! So don't think it's related to the conversion. It's defiantly more refined, have you tried throttle body alignment? And also checked if your lambda is in tolerance?

Club Chairman

[EnthusiastOwned 7]

I'm down on power and misfire top end, currently at stealth having new head! So don't think it's related to the conversion. It's defiantly more refined, have you tried throttle body alignment? And also checked if your lambda is in tolerance?Club Chairman

What's your reasoning for having a new head then? I only ask because I know a stem seal on mine has gone dry and I due a head rebuild. I have a refurbished head ready to fit but I'm holding out until better weather.

Yep, throttle body is aligned and confirmed with vagcom. It's all clean and not sticking anywhere. Vagcom confirms part / full throttle and overrun modes. It opens fully with the pedal.

How can I check to see if the lambda is in tolerance?

[VR6Pete 1,455]

What's your reasoning for having a new head then? I only ask because I know a stem seal on mine has gone dry and I due a head rebuild. I have a refurbished head ready to fit but I'm holding out until better weather.

Yep, throttle body is aligned and confirmed with vagcom. It's all clean and not sticking anywhere. Vagcom confirms part / full throttle and overrun modes. It opens fully with the pedal.

How can I check to see if the lambda is in tolerance?

It's done 120k, exhaust valve guides need doing after 80k as they start wearing, plus the mating surface on my old head was really pitted oh and it's using a crazy amount if oil, I'm told around 75% of oil consumption issues are usually remedied with head rebuild unless your bottom end is buggered, but won't know until the head is off anyway, but looked ok visually when I last checked, could still see honing marks in the bores!

You need use vag-com and setup the measuring block, can't remember which one it is though mate sorry.

Mine only ran 186bhp before remap and with schimmel cams and only 194 after a remap, something wasn't right so didn't push it any further.

Club Chairman

[leespiro 9]

u just having standard springs etc

[VR6Pete 1,455]

Yeah I'm NA at mo, won't be going for big power if/when I do boost it

Club Chairman

[EnthusiastOwned 7]

Rightio, 

 

I put my car on Vagcom last night, 

 

I got one fault code: 

01247 - Activated Charcoal Filter (EVAP) System Solenoid Valve 1 (N80) 37-10 - Faulty - Intermittent

 

I presume this is the little blue valve on the wing which opens and closes for the charcoal canister? Could this be causing my issues?

 

As for the Lambda:

 

O2 Sensor was fluctuating around 1.6% to -3.1% on idle (720-760rpm). Voltage was 0.070 to 0.825v on idle. I've gone and bought a genuine one from TPS anyway, as I don't know how old it is.

 

Thoughts people?

[VR6Pete 1,455]

Rightio,

I put my car on Vagcom last night,

I got one fault code:

01247 - Activated Charcoal Filter (EVAP) System Solenoid Valve 1 (N80) 37-10 - Faulty - Intermittent

I presume this is the little blue valve on the wing which opens and closes for the charcoal canister? Could this be causing my issues?

As for the Lambda:

O2 Sensor was fluctuating around 1.6% to -3.1% on idle (720-760rpm). Voltage was 0.070 to 0.825v on idle. I've gone and bought a genuine one from TPS anyway, as I don't know how old it is.

Thoughts people?

I have read somewhere that when the evap valve isn't operating that it stops your ECU adapting / learning - could be wrong though lol, I'll have search through.

I'm sure someone like @UnitedMotorsport can confirm if those values are expecting!

Club Chairman

[UnitedMotorsport 55]

I have read somewhere that when the evap valve isn't operating that it stops your ECU adapting / learning.

This is correct. Long term fuel trims will not set with an N80 error.

 

O2 Sensor was fluctuating around 1.6% to -3.1% on idle (720-760rpm). 

 

Nothing wrong with that.

[EnthusiastOwned 7]

That'll be why my O2 adapted settings were non existent then.

Looks like I've just wasted £150 on a new lambda too! Doh!

Does a failed solenoid valve explain my symptoms though?

[EnthusiastOwned 7]

Found a new solenoid valve, just waiting for it to arrive.

Last night when driving the car, tootled around under 3k rpm until it was warmed up, no issues. I then put my foot down and the car instantly bogged down - severely. The car just had no power, it was struggling to rev at all and even at 40mph, 2nd gear, it was struggling to keep that speed. After about 30 seconds I pulled in and with the car idling I sat there scratching my head. I decided to limp home so turned the car around and the car was back to normal. It just felt like a hiccup. Bizarre.

Any idea what it could have been and do you think it's related to my issues?

[ASHLEYG 4]

Haven't got a partially blocked exhaust have you?

[EnthusiastOwned 7]

Haven't got a partially blocked exhaust have you?

 

Good question.

 

I had an old Polo GT which suddenly lost all power whilst on the motorway, literally wouldn't go over 70mph. But it still drove really nice and smooth, it felt the same but with half the BHP. I noticed that the exhaust kept blowing at the downpipe and on cold morning's and the condensation would come from there instead of the tail pipe. That turned out the back box internals had disintegrated and blocked the system.

 

But I don't think that's the case here as it's more engine hesitation and poor running rather than just down on power.

 

I'll give the exhaust a good looking over at the weekend. Although I'm unsure of any ways to actually test the system?   

[EnthusiastOwned 7]

Bit of an update on this..

 

I've fitted a genuine Lambda Sensor as it had a NGK one in there. No difference what so ever. Very similar readings on VAGCOM from both sensors. Anyone need a working Lambda then? 

 

I reset the ECU.

 

I then fitted a new genuine blue temp sensor, changed both knock sensors for good genuine used items from a '97 VR6 and I also changed the crank sensor from the same car but it wasn't genuine, although looked very new. Started the car and it idled ok for a few minutes then cut out and wouldn't start, VAGCOM pointed to the crank sensor. I swapped back the old sensor (albeit cleaned up) and took it for a spin. It drove really nice, all my power was back and it pulled like a train, it pulled insane really. But then, after about 30-60 mins of driving it seemed to hold back and refrain itself again. It's not as down as it felt before, it still pulls very hard, it just seems to be holding back from when I first started it after fitting the above. Possibly something to do with the ECU learning and adapting? (on that note, the ECU still doesn't adapt and keep the values for the lambda).

 

Any thoughts?   

[mattvr6 133]

Maybe ur crank sensor is breaking down when it gets hot old vauxhalls used to suffer with this and my old refdtop corsa did aswell did exactly what ur saying

Sent from my iPhone using Tapatalk

[EnthusiastOwned 7]

I think a new crank sensor would be next on the list.

Bit of an update..

I've fitted a replacement EVAP valve and it works as I can hear it clicking. The ECU now learns lambda settings.

Also, I had a play about with more vacuum stuff and the pipe from the FPR to inlet just ripped in half. Hmmm.. Possibly the issue?

Fitted a new one and went for a drive. Seems more pokey and idles better. The exhaust is more raspy now and pops on the overrun like it used to. Still doesn't seem 100% though.

And now to top it off when I start the car the RPM's drop to almost stalling point and rise to a healthy 720rpm. Only does it in start up. Any ideas?

Edited March 1, 2014 by EnthusiastOwned

[EnthusiastOwned 7]

Final update.

I reset the ECU once more, performed the standard adaptations, throttle body etc. let the car idle for a bit and went for a drive to set all the ECU learning.

The car now pulls like a train. Idle and start up are perfect. The power delivery is progressive and the car pulls from 1,000rpm through to redline without a hiccup.

It was definitely the FPR vacuum hose causing the majority of power issues and lumpy idle, the dead OBD1 EVAP solenoid was causing the ECU not to learn values which was rectified by a replacement OBD2 solenoid. All the other senders and switches just helped with matters but weren't necessary. Then the ECU needed a good reset to bring everything in line again.

I can't get over how smooth the engine and power is with a the new senders and switches. Plus the Bosch Motorsport coilpack and Magnecor HT leads have made such a huge difference to top end pull.

Edited March 5, 2014 by EnthusiastOwned

[Therusterman 59]

Glad you got this sorted

[EnthusiastOwned 7]

Thanks.

It's always the little things. I didn't really check the FPR vacuum hose as I replaced it for a new one around 12 months ago, it looked perfect but the rubber insides were rock hard and perished. Genuine VW stuff too. Think I might get some silicone hose.