Compression for an obd2

[tombell999 0]

My car is running quite lumpy, possibly missfiring. Just wondering what the compression is meant to be at for an obd2? I think one of mine was around 150 and the rest were 160 ish any help would be good thanks

[CorradoVR6-Turbo 0]

150 is a little low but should not cause any poor runnings,the cr for the vr is around 160-180.

[tombell999 0]

Is there anyway I can improve that compression without piston rings head gasket etc? Will the arp bolts help?

[CorradoVR6-Turbo 0]

No as its down to cylinder sealing,bolts dont do a thing there,its removal of head,valves cut and ground,pistons out and bore with new pistons and rings mate...but as i said 150 is still good for a vr.

[tombell999 0]

Oh rite ok thanks for your help James. Now let's find the real problem!!

[CorradoVR6-Turbo 0]

check the coil pack and lead,plugs etc mate,you got a obd port to check for codes?

[tombell999 0]

All the leads, plugs etc seem ok? Haven't checked coil pack tho. It's a strange miss it's not a missfire like it's running on 5 cylnders only a slight one. Obviously it's not as fast as it was. I really don't know what it could be? And I don't think it has. It was a conversion from an early valver so no diagnostics slot under the gear gaitor, which makes it a pain in the ass!

[CorradoVR6-Turbo 0]

Have you tried a compression wet test to find out if its valves or rings?

[Flexso 0]

Hi Tom,

 

Thats sad to hear mate. Does that mean its not going down santa pod this year?

 

Is the hesitation at low revs? Is it continual?

[andy 0]

I would say all your readings are low, every VR6 I've measured (several) have been up arround the 180 - 190 psi mark. If all of yours are arround the 160 mark then I would say you have a problem there straightaway. Was the engine hot, throttle wide open?

[Kevin Bacon 5]

If they're all low, could be tired valves not sealing properly, or even a badly calibrated pressure tester. A leak down test is the only way to find out for sure - other a strip down and visual inspection.

[andy 0]

If they're all low, could be tired valves not sealing properly, or even a badly calibrated pressure tester. A leak down test is the only way to find out for sure - other a strip down and visual inspection.

Indeed, I'd want to check the valve timing too.

[Kevin Bacon 5]

/\ Yeah I was thinking that too, but I kind of assumed the engine was original and untampered with.

[tombell999 0]

thanks for all your help guys. ill give my mechanic a ring today and see what he says about it. cheers guys! oh and yer i prob will still be running down the pod mike! gotta try the new cams! :)

[Flexso 0]

thanks for all your help guys. ill give my mechanic a ring today and see what he says about it. cheers guys! oh and yer i prob will still be running down the pod mike! gotta try the new cams! :)

 

legend! 15 dead is pretty dam good for standard away.

[tombell999 0]

for a standard 2.8 anyway! hope to get into the 14s next time! anyway ill keep everyone updated on what happenes! :)

[tombell999 0]

........got the car back still lacking in second gear! i cant beleive it! ill take it out tomorrow and let you all know.

[tombell999 0]

ok i took it for a little drive this evening. i got in the car and started it up and noticed how much the exhaust is spluttering with a lot of fumes coming out (more than there should be) could this be that the car is running quite rich and therefore overfuelling causing it loose power? i also noticed my petrol went down quite a lot to! any advice?

[Kevin Bacon 5]

Need to get it on VAG-COM really....

 

The two most common causes for that are a dead lambda sensor and / or a dead cam position sensor. The next favourite if it's not those two is a dead MAF sensor, which if you have the OBD2 ECU to go with the OBD2 engine, it will tell you (unlike OBD1).

[tombell999 0]

oh rite ok thanks. does the vag-com plug into the ecu?

[Kevin Bacon 5]

I should have looked at your sig really. Didn't realise this is a VR6 conversion!

 

It does indeed plug into the ECU, via the OBD port under the gear lever panel. Whether or not the ECU comms wire was connected to that during the conversion or not, I couldn't tell you!

[tombell999 0]

Well the problem is it was origionally an early 1.8 so there isn't a port.... Oh well I guess I got to change everything until I find out what the problem is. I'll start off with what you said first though. Thanks kev :)