VW T4 Forum - VW T5 Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
26 Posts
Discussion Starter #1
Hey!
just fitted my intercooler today to my 88bhp 2002 2.5 AJT engine in preparation for PP2. As I went off for my test drive I was rather disappointed to find out that instead of extra performance I seem to have lost power from the 3rd to 5th gear...
It accelerates and revs fine in the first couple of gears but just runs out of steam above 2400 revs in the higher gears and I seem to have lost about 10 - 15 mph at the top end.

It's a original vw intercooler with original pipes and I removed the sound proofing strip under the bonnet to help the airflow get to the intercooler. The 4 pin socket was missing when I bought the intercooler and was sent a aftermarket (non VW) socket which I have fitted.

It feels like the turbo isn't realy spooling up, I've checked for air leaking from the pipework and don't really know what else to do. Does anyone have any ideas? :confused::confused::confused:

Thanks
Andy
 

·
Registered
Joined
·
112 Posts
Try fitting your original 4 pin socket to the cooler, if the aftermarket one is faulty it wont register boost pressure and therefore wont inject the right fueling for the boost pressures, put a 102 cooler kit on my 2002 ajt motor and went ok.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #4
Hey guys, thanks for the replies, unfortunately i don't have a vagcom. I'm guessing a garage well charge for the privilege of using theirs...anyone around between Oxford and Cheltenham that would be are to do a vagcom reading?

interslice, thanks for confirming my thoughts, i didn't think it was a complicated error and as i can't find any any air leaks or visual damage to the intercooler i guess it must be the socket.

Jb2.4 Unfortunately the socket in the old pipes is a slightly different size :( so will have to order a new VW one and hope this solved it.

Thanks Andy
 

·
07415125940
Joined
·
6,699 Posts
Try fitting your original 4 pin socket to the cooler, if the aftermarket one is faulty it wont register boost pressure and therefore wont inject the right fueling for the boost pressures, put a 102 cooler kit on my 2002 ajt motor and went ok.
Agree with this. You can use the housing from the boost pipe that was there before you removed it to fit the IC as opposed to the one in the intercooler to test it.
 

·
Registered
Joined
·
26 Posts
Discussion Starter #6
Hi again,

as you can see on the photo the diameter of the 2 sensors are different, the IC sensor has a bigger diameter. I didn't think it would seal properly but tried your advice Ron on testing it with the old sensor and A: my lost horses have found their way back again and brought some friends T: Revs are back up again, I can hear the turbo spool up again and my top speed has recovered. I'll order in a genuine VW sensor now and enjoy the benefits of an IC :cool::cool: PP2 next month LOL:

Both sensors look quite different and initially I thought there might be a plastic cap on the new sensor which would explain why it isn't reading properly, but on close inspection I haven't found a way of removing a cover of sorts. Any ideas?

And just out of interest and to expand my knowledge ;) What does the MAP sensor do, does it just measure boost pressure or does it have any other functions too? And the same for the MAF sensor, does that just measure ambient pressure?

 

·
Registered
Joined
·
112 Posts
MAP sensor or manifold absolute pressure, measures the boost pressure in the inlet system from the turbo, on the 2.5 ajt you can have a 2 or 4 pin sensor, one measures pressure and temperature of inlet (4 pin) the other measures temperature (2 pin) pressure is measured by the ecu directly via a pipe. The MAF sensor or mass air flow measures the amount of air flow into the engine.T:
Hence why if your aftermarket sensor was faulty then boost pressure would not be sensed and fueling would not be upped to compensate for boost or, if the sensor was faulty and reading too high it would shut the boost right down and probably go into limp mode.
 

·
Registered
Joined
·
724 Posts
There are 2 sizes of map sensor holes accross the vw range, t4s use the smaller. The map sensors are also ranged to certain pressures so arunning higher boost will have amap sensor which can measure that range. The one on the intercooler might be in working order just not the right pressure range. you will need to fashion a way to fit the small maf securely.
 

·
Registered
Joined
·
112 Posts
There are 2 sizes of map sensor holes accross the vw range, t4s use the smaller. The map sensors are also ranged to certain pressures so arunning higher boost will have amap sensor which can measure that range. The one on the intercooler might be in working order just not the right pressure range. you will need to fashion a way to fit the small maf securely.
Didn't know that, learn something new every dayT:
 

·
Registered
Joined
·
26 Posts
Discussion Starter #11
Some good info coming up, thanks!

I did indeed remove the plastic cover Jimmy James, however i couldn't figure it how to fit the scoop that i ordered through VW. Got the part number through the forum and made sure i had the right size as there are three different ones. The scoop slides in the slot alright but can't close the bonnet with it fitted so left it out to sort on a later day (can anyone post a pic of it fitted?).

Bigyeti, you say there are two sizes and t4s use the smaller one, if that is the case, why does the intercooler i bought (a original t4 one) have the bigger hole?

Have fitted the smaller one for the time being as a temporary fit until i can source a new one and does the job without leaking. :cool:
 

·
Registered
Joined
·
724 Posts
HA ha, I'm learning too, seems that both large and small were used depending on age:

Large hole 038906051 thrust sensor / F 70-X-250 001>>*70-1-200 000/ AJT,AHY,AXG

Small hole 038906051B thrust sensor / F 70-1-200 001>>*/ AJT,AHY,AXG, AYY

Didn't know they did big hole ones for a while...
 
1 - 13 of 13 Posts
Top