Cat question and engine faults

[AJ_EQ 0]

Hoping someone can help me with this.

 

I own a '93 Reg VR6 and had a few questions about the Cat.

 

I've been having terrible MPG. Averaging 15.65. I didn't expect it to be fuel efficient, but it's a little annoying when I can't even get 300 miles out of a tank.

 

I assumed that a '93 VR6 would come with a Cat as standard, but according to my mechanic (im not hugely knowledgeable), it has been removed, I'm guessing in order to improve bhp. My first question is should I splash on a Cat or leave it as it is? Would leaving it as it is have a huge effect on my fuel economy?

 

Had the engine scanned twice, which showed:

0515 Hall Effect Sensor

0533 Idle Speed Regulator

0537 Lambda Control Function

0513 Engine Speed Sensor

(0537 and 0513 disappeared on the 2nd scan)

 

With regards to the engine codes, I just wondered what would be the next step to take?

 

Thanks

[Reggit 0]

With no CAT, it may well (read most likely) fail it's MOT on emmissions.

 

Engine speed sensor (crank sensor) will always come up if scanned with the engine stopped, it should go once it is running. If it shows as intermittent, then likely that it is or has been faulty in the past.

 

Best bet is to clear the codes and take it for a run then rescan to see what has come back and is genuine. The ECU will keep old faults in it's memory unless cleared.

[AJ_EQ 0]

ECU was cleared and rescanned, which just showed 0515 and 0533. Could either of these be responsible for such high fuel consumption?

 

Also what would have happened to the lambda sensor if the Cat was removed? As far as I understand it is located on the exhaust line somewhere.

 

It only had a MOT a couple of months back, just before I bought it, am surprised that it made it through.

The exhaust fumes smell really rich, which I understand could be the result of a failed lambda sensor, but this came up in the scan the first time, but not the second.

[Alex_G60_Fanatic 0]

lambda is on the exhaust just after the Manifold i think. A faulty Lambda could cause you to run rich for sure...

[AJ_EQ 0]

Do think the fuel could be running rich due to these two faults?

0515 Hall Effect Sensor

0533 Idle Speed Regulator

 

The Lambda fault disappeared once it cleared and rescanned. I just dont want to have to pay out for a lambda I dont need.

Also putting a Cat back on is going to cost a fair bit, but if its not going to pass its MOT, then I will have to regadless.

 

Do you think not having a Cat could affect the fuel consumption heavily?

[AJ_EQ 0]

lambda is on the exhaust just after the Manifold i think. A faulty Lambda could cause you to run rich for sure...

So the Lambda should still be there, even if the Cat has been removed?

 

What are your opinions on running it with/without Cat? Can anyone tell me how to solve the other faults and where about there sensors/units are?

 

thanks again

[RW1 0]

0515 Hall Effect Sensor

0533 Idle Speed Regulator

 

00515 - Sender located behind and slighty the coil pack, assumption its a late VR6 engine. Its pushed into the cam shaft in the side wall of the head. Has a 3 wire plug connection. Known to be poor. Results in the ECU going into Limp Home Mode and leaves the engine feeling like its loss a cylinder plus limits max rpm for safety.

 

The fault can also suggest the chains have jumped a sprocket. Not bump started it recently???

 

00533 - ISV vlave. Most likely sticking, explains the low idle and lumpy/missing a beat running. Needs a clean or just exercise it with Output Test in VCDS for about 3 mins and let it click away. See here.

 

Either only affect fuel consumption by a small amount , less than 1 mpg.

 

Lambda needs to be there, in the exhaust gases, to close the fueling feedback loop.

 

.

[Reggit 0]

When you did the 2nd scan, was it immediately after clearing the faults? If so there is a good possibility the lambda won't have re-appeared (if faulty) drive it for a few miles and then scan again.

[AJ_EQ 0]

Seems like 0515 and 0533 wont be responsible for my extremely poor fuel consumption. Worth replacing anyway?

Yes I did the second scan straight after I cleared the first one. I shall take it for a longish run before I see my mechanic on Mon.

Any more info on the lack of Cat? Mot requirements, could this be the reason for poor fuel consumption?

[RW1 0]

Seems like 0515 and 0533 wont be responsible for my extremely poor fuel consumption. Worth replacing anyway?

 

0515 = Yes cos it's down on power otherwise. Camshaft position sensor 021 907 601A. Once replaced, clear the fault to regain the ECU onto normal operation.

 

0533 = Exercise it as per link. Look up "Cleaning ISV" on here. VW ISV part price closing on £300. Or http://cgi.ebay.co.uk/Idle-control-valv ... 2eb0ead093 - Chinese copy.

 

.

[Supercharged 2]

Seems like 0515 and 0533 wont be responsible for my extremely poor fuel consumption. Worth replacing anyway?

Yes I did the second scan straight after I cleared the first one. I shall take it for a longish run before I see my mechanic on Mon.

Any more info on the lack of Cat? Mot requirements, could this be the reason for poor fuel consumption?

 

Can't help and you need to fix these before investigating anything else really - the VR6 should give between 30 - 35 mpg easily if running right

[AJ_EQ 0]

Thanks for all the advice guys.

 

I'm going to work through each of the faults one by one, starting with replacing the camshaft position sensor next week.

 

Was also wondering if any of these engine faults could cause an erratic idle/cutting out? This only happens in the morning mind, when the engine is cold. It's not a major problem right now, but would quite like to sort it.

[AJ_EQ 0]

In my quest to have a smooth running reliable corrado, I still have not made any headway with this problem.

I put in a new camshaft sensor, which made no difference to anything (was hoping for a little more power :( )

 

I dont really fancy spending out on isv, when it may not even be the cause of my poor fuel economy. I also did a round trip to leeds and back (320miles), visiting the gf , which cost me a nice tidy sum. Averaging 13.6mpg :brickwall:

 

Not really sure now what steps to take to determine the problem. :shrug:

 

Also erratic idle and stalling has increased.

 

want to spend money on other parts for her, not double fuel costs.

[AlgarveVR6 0]

I had a free flow sports cat put on. Used old pipes, and cut out and rewelded in free flow bit. Nice job.

made a noticable difference and passes MOT etc

Was about 250 bucks me thinks but that was 4 years ago

[somersetdub 0]

Exhaust gas analysis would give a good idea as to what's going on.

 

You could have a slight misfire or maybe a vacuum leak?

The lack of cat shouldn't make fuel economy worse.

[coullstar 0]

00533 - ISV vlave. Most likely sticking, explains the low idle and lumpy/missing a beat running. Needs a clean or just exercise it with Output Test in VCDS for about 3 mins and let it click away. See here.

 

 

 

Do this next, should help with the idling and stalling issues. If it were me Id change out the lamda as well. Im assuming your using the mfa for the mpg reading so have you double checked it with your own calcs?

[AJ_EQ 0]

Havn't gone by the mfa, knowing its unrealiability. Only by my own calculations. It would be nice to drive the vr6 how its supposed to be driving, but currently I honestly drive like a granny to use as little fuel as possible.

 

Have given the isv a good clean= no difference at all.

 

Thinking the fault could lie with the lambda sensor, but no notification of that on the vag-com. Where abouts is it located? Maybe I can test it somehow?

 

also have been reading about the MAF, which Im also not sure of its location. Any way of testing this?

 

havn't noticed/heard any air leaks. all hoses/pipes are tight. Is there any reason I should replace the HT leads? as I dont think they've been replaced at all (123,000miles on clock). What about distributor caps and rotor arm?

[somersetdub 0]

If it's definitely not misfiring, then it's doubtful leads etc would make a huge difference, but it might be worth looking in the dizzy cap to check for any obvious corrosion etc.

Also you could take the plugs out to see if they're all the same colour/correct colour.

Maf can definitely cause rough running, but it should show up as a fault code if it's faulty, as should the lambda.

[Reggit 0]

I have a feeling that a faulty MAF won't show on Vagcom - a failed lambda does. The lambda probe is located on the CAT, or in your case should be screwed into the cat bypass pipe.

[AJ_EQ 0]

Is there anyway to remove the ht leads and sparks without the tool? It probably makes sense to buy one, but just so I can take a look today.

Also would it be worth replacing the isv, would this most likely be responsible for 00533, even after I've cleaned it?

[Kevin Bacon 5]

So is your VR6 a Dizzy or Coilpack model? As it's a 93, quite likely to be a Dizzy one. Either way, the Hall sensor being out will overfuel in a big way.

 

Trying not to get all technical on you but no hall signal = no sequential injection. Your engine will be running rich. The lambda and idle speed faults are secondary errors relating to the over fuelling because they're having to work outside of their normal operating parameters.

 

Replace the Cam sensor / Dizzy hall sender and all should come good again. Not to mention reclaiming your lost 30hp.

[AJ_EQ 0]

lol at my knowledge on vr6. I pretty sure my mechanic mentioned something about the coilpack. Im also fairly certain its an early '93 if that helps. Am going to replace plugs.

 

Have already replaced cam sensor and cant say i noticed any difference at all. Other than code disappearing.

 

Any idea what to check next? Stupid 00533 code. Poor idling again this morning.

[Roger Blassberg 0]

When you replaced the cam position sensor, did you also replace the trigger wheel on the camshaft? Are you sure that the CPS is working? The wiring in the loom that runs along the injectors and goes back to the CPS was in a bad way on mine until I repaired it, so that's worth a check.

 

My concern is also that, in using so much fuel, you are washing the oil from the bores and diluting your oil generally.

 

The MAF is not picked up by the VAGCOM so far as I know; a rough and ready check is to disconnect its electrics when the engine is running and listening for a noticeable drop in idle quality.

 

To be honest, this does sound like lambda related trouble. Even if the sensor is ok, the wiring could be a bit ropey.

 

Let us know how you progress.

 

Best wishes

 

RB

[AJ_EQ 0]

Replaced plugs this morning, no difference. Not entirely sure how to test the CPS, Im guessing voltmeter, which I dont currently own, might be worth investing in one. Took a look at the wiring loom and visually its looks alright to me. There was one suspect wire, though not from the CPS. Bear with my poor mechanical knowledge. The wire was plugged in to a cylindrical unit, vertically positioned just above the coilpack. Had a two prong connector, plugged in vertically, with no clip, quite small, barely 10mm across. Anyhow it was a little loose, so pulled it out, cleaned it bit, because it was slightly corroded at the end, then put it back. Any idea what this was?

 

Did your test Roger on the MAF, as soon I removed it, turned it over, the engine almost cut out instantly, so Im assuming MFA's not faulty.

 

Couldn't find the Lambda, does the car need to be up to get access to it?

 

I did not replace the trigger wheel on the camshaft, as I have no idea how to go about doing this. What could replacing this achieve?

 

From reading around it seems I should have noticed an increased BHP from replacing the CPS, I'm guessing theres something not right with it still.

 

All replies much appreciated as always.

 

Thanks

[AJ_EQ 0]

I just thought could it be the injectors (hope not)..?