52 replies to this topic

[The Batman]

Or map sensor

[The Batman]

Or air temp sensor

[mbes2]

After another new MAF, issue the same... 

 

Doing some reading about such symptoms, only when the MAF is connected points to a earth issue as the temp sensor / MAF & Lamba are on the same part of the loom (So ive read and understood)

 

Fed up with the crap eng bay access so will remove rear clam again to check everything

 

Should be fun in a cold garage

[mbes2]

Latest update, tested a 100% working MAF and issue went away on the first non-clam drive test....

 

Refitting clam Thursday for test two.

 

Oh SO much fun, if this is the fix then I've had 3 faulty MAFs

 

[Andy_VX]

I wouldn't be surprised, they're so temperamental! I had 2 faulty ones and like you, spent ages pissing about checking all the pipework!

[Nev]

MAFs are the evil love child of Euro3 and 4 etc! Best off eliminating them IMO as they are so fickle, maybe you should consider swapping to stand alone ECU mate?

[The Batman]

What air filter setup do you have as this could be the reason

[mbes2]

What air filter setup do you have as this could be the reason

apexi air filter but it's been on for about 3 years now without issue.. I'm trying to work out where to relocate the relays, ecu can stay attached to back of boot. I've got some loom tape to tidy things up so will sort that before putting clam back on. 1 of the mafs was a silly cheap new ebay special. .. which I know made things worse

Edited by mbes2, 16 December 2015 - 10:05 AM.

[siztenboots]

Please check the cam timing , just pop the top cover off and turn crank pulley clockwise.

[bladerunner1000]

I do wish I had seen this thread before buying Marks car, or he could have told me why the MAF was disconnected!  Oh well, it seems to be my problem now.  Let the cut knuckles and swearing begin at the weekend.  I am lucky to have 2 VXT's so it looks like there will be plenty of part swapping to find the route cause.  Does anyone suspect the map may be at fault?? 

 

[Nev]

If he kept getting MAF failures, it is either because he was buying cheap pattern parts and/or the Apexi air filter is not doing it's job and allowing the very delicate platinum wire in the MAF to be contaminated with crap.

 

Possible solutions (assuming the fault genuinely lies with the MAF):

1. Eliminate Apexi air filter, replace with OEM air box, buy genuine MAF.

2. Eliminate MAF, install 3rd party ECU that doesnt need one. Side benefit = far better boost/power control.

 

 

 

 

Edited by Nev, 26 April 2016 - 07:29 AM.

[bladerunner1000]

Everything I have read online leads me to believe that its either a boost leak or Pre-cat Lambda sensor issue.  I have also read threads on several forums for the Z20LET with people chasing their tails around the engine bay trying to find out why they have a P0170 fault.  Annoyingly everybody posts their problems but not how they repaired it, lol.  Am I right in thinking the car will run a safe map if the MAF is disconnected?  I don't really want to drive the car until this issue is sorted or those pretty forged internals may be turned into rather expensive scrap metal. 

[Nev]

Everything I have read online leads me to believe that its either a boost leak or Pre-cat Lambda sensor issue.  I have also read threads on several forums for the Z20LET with people chasing their tails around the engine bay trying to find out why they have a P0170 fault.  Annoyingly everybody posts their problems but not how they repaired it, lol.  Am I right in thinking the car will run a safe map if the MAF is disconnected?  I don't really want to drive the car until this issue is sorted or those pretty forged internals may be turned into rather expensive scrap metal. 

 

Not many solutions out there because not many people fully understand the mutual relationships and functions of the sensors and systems that govern boost on the car, it is more complex than it seems at times. I've fiddled with the Z20LET more than most and I still make oversights.

 

The car should run perfectly safely with the MAF un-plugged (so long as the MBR map has not made a change to the closed to open loop logic that is used as a backup when it is disconnected/failed).

 

I have sent you 2 PMs BTW.

 

Basically there are 2 mechanical ways boost can be incorrectly bled, firstly by bypass valve, secondly by wastegate valve. It's likely to be related directly or indirectly to 1 of those 2 systems. The alternative reasons is that ECU is doing something unexpected due to 1 or more faulty sensors (eg lamda) feeding it incorrect info.

 

Ulimtately, if you replace all pertinent sensors and check the physical operation of the bypass and wastegate valves then you will solve the problem. Easier said than done though !

 

GL.

Edited by Nev, 26 April 2016 - 04:20 PM.