# obd1 - - vr6 throttlebody on 2.0l - - TPS questions



## urogolf (Dec 10, 2000)

i am using a vr6 throttle body on the 2.0l in my rabbit attached to a custom short runner
having throttle issues.. 
the only rev range that revs smoothly is the mid throttle position
upon full throttle the revs just die 
part throttle it loads up
i have had the power wires switched on the tps to account for "reverse direction" opening situation and the situation was still the same
we busted out the bentley and ran some troubleshooting tests off the ecm connector and the resistance readings were out of spec. and the way I have it wired the tps is reading backwards.
i snagged another used tps last night and am going to try that one tonight and see what happens
could a bad tps cause this?
this tps was known "good" on this motor when it was a stock 2.0l
here are some specs on the setup.
1995 aba (complete)
1994 obd motronic harness
p&p & decked head
TT 276 cam
Short runner manifold
Vr6 throttle body, MAF and 3 inch inlet tube
TT chip for said cam, t-body and inlet tube size
dont mind the ugly valve cover (its no longer on there)


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## Crubb3d Rymz (Dec 25, 2006)

*FV-QR*

i dont have any info to add except for damn...thats my dream aba setup http://****************.com/smile/emthup.gif


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## urogolf (Dec 10, 2000)

*FV-QR*

thanks you bud!


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## MecE2.0 (Dec 20, 2005)

*Re: obd1 - - vr6 throttlebody on 2.0l - - TPS questions (urogolf)*

hmm. interesting. not sure if you actually need to switch the power wires. even though the TB opens reverse, it reads the same as far as i know. the other thing is the chip. is this a custom done chip to account for the 3" maf/inlet/tb or is it something they just don't carry regularly? also, whats your IAC situation?


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## urogolf (Dec 10, 2000)

at the ecu connector all the resistance readings were backwards.. decreasing instead of increasing..
i imagin that'd be an issue
i rewired it correctly (switched the outer 2 wires on the plug) and it the values read correct now.
fixxed some timing issues and the car runs better
i think i have a maf issue still as the one i got doesnt spec out as the bentley says it should
the chip from TT is spospedly set to account for the big t-body and maf and 276 cam, as its how i ordered it. 
dunno if they actually made it correct or if its an off the shelf cam chip


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## MecE2.0 (Dec 20, 2005)

*Re: (urogolf)*

the MAF will definitely cause some running issues. how is it running with the MAF unplugged? is this a 2.0 MAF in a 70mm housing or a stock vr MAF? also, if the IAC was deleted (as often happens with SRI's) is there a resister inline to trick the ecu? without you could have some idle issues.


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## urogolf (Dec 10, 2000)

*Re: (MecE2.0)*

The iac is there and functional (noticeably different idle with it unplugged)
the maf is a 2.0l one built into the 3.0 inch inlet tube that attaches to the throttlebody with a sealed v-band clamp








the car wont idle (for long anyways) with the maf unplugged
this maf is out of spec according to the bentley so i am in the hunt for another good OBD1 one, 

are the obd1 & obd2 mafs the same? i dont think they are but who knows


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## MecE2.0 (Dec 20, 2005)

*Re: obd1 - - vr6 throttlebody on 2.0l - - TPS questions (urogolf)*

i assume you're running an adjustable cam gear, what do you have it set at?


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## urogolf (Dec 10, 2000)

*FV-QR*

yep
set to _"0"_


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## urogolf (Dec 10, 2000)

*FV-QR*

the thing that bugs me is that this harness ran this car with a stock 2.0l last year with no issues
everything the same except head, cam intake manifold and t-body
even the same maf but in this housing


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## MecE2.0 (Dec 20, 2005)

*Re: FV-QR (urogolf)*

k, well this probably isn't the only issue, but with a decked head you're actually going to be out on your timing if you set it to 0* (assuming you used the marks). good thing you have an adjustable gear on there. another question, how was the egr delete handled?


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## urogolf (Dec 10, 2000)

obd1 has egr?


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## MecE2.0 (Dec 20, 2005)

*Re: (urogolf)*

yeppers. pesky little things. the delete is easy though, basically its just remove it and plug the holes (already taken care of on yours) then clip and cap the wire going to the ecu. theres a diy or two floating around, search the 2.0 forum archives.


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## urogolf (Dec 10, 2000)

Yes!
that wire was clipped from the harness when installed


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## urogolf (Dec 10, 2000)

*FV-QR*

had reset cam timing and dizzy timing and the car was better (timing was way off for some reason)
idled great and drove funny like i could feel it holding back, letting go and holding back and bucked under light load..
today i put in an OBD1 vr6 maf
pulls perfect all through all throttle positions and loads but idles funny now
i can deal with the idle
gonna try and tweak the idle a lil more


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## MecE2.0 (Dec 20, 2005)

*Re: FV-QR (urogolf)*

getting that timing right with a decked head can be tricky. so were you originally trying to run an obd2 TB? that'll mess things up a little. they're made to control the idle as well and close differently. so what do you mean by funny idle? with that cam and the head work a good buck is always going to be there. you can always tweak the screw on the side of the TB, although the better bet would be to send the chip back and get TT to change it. even obd1 is going to try turn everything back on you with the IAC


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## urogolf (Dec 10, 2000)

no the t-body has always been an obd1 vr6 one.
the maf was an obd1 2.0l one
i switched to an obd1 VR6 one and the car pulls and drives nice now..
i am going to tweak the idle screw a lil bit more


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## MecE2.0 (Dec 20, 2005)

*Re: (urogolf)*

ah. see i had expected that, but was a little confused as to whether or not it made a big difference (thought it was all in the housing). sweet. gives me ideas for my 16ABA.


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## urogolf (Dec 10, 2000)

yeah i though it was just housing size too
gonna see what tweaking the idle screw does for my idle.. (likes to die and idle super rough)
i have wanted to do an aba 16v for a long time
maybe when i get "bored" with this setup.. this is the 4th engine setup in the car since i have owned it


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## urogolf (Dec 10, 2000)

*FV-QR*

just got off the fone with a reputable local VW tuner (rui from RM protune)
he advised me to reduce the inner diameter of the inlet tube to that closer to an aba one, and see what happens
gonna try that tomorow


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## MecE2.0 (Dec 20, 2005)

*Re: FV-QR (urogolf)*

well if TT did actually flash the chip to run the bigger MAF/TB there shouldn't be much of an issue. worse comes to worse you could make an adapter for the mani and run all the aba intake plumbing, would get rid of all the issues (just wouldn't be as awesome).


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## urogolf (Dec 10, 2000)

true


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## urogolf (Dec 10, 2000)

*FV-QR*

ok
combo deal!
got another obd1 vr6 maf and plugged it in
car fired right up and went to idle.
drove it and it broke up again
i inserted the 1/4 inch thick silicone coupler into the pipe thus reducing the inner diameter of the pipe by 1/2 inch to just under 2.5 inches....
and presto!
perfect lumpy idle and drove great. didnt break up at all and pulled nice through 1st-3rd
thanks for lettin me pick your brain MEC http://****************.com/smile/emthup.gif


_Modified by urogolf at 9:24 PM 9-22-2009_


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## MecE2.0 (Dec 20, 2005)

*Re: obd1 - - vr6 throttlebody on 2.0l - - TPS questions (urogolf)*

no prob. this is something i've been thinking about for the 16vABA i'm slowly (moving at the speed of pick'n'pull) putting together. figured since i plan to run an sri why not go with a different TB. suppose i could use whatever i want with MS but i kinda want to keep the mot2.9 so i think i'll probably de-ramp and trim the butterfly carrier and then just give everything a good polish.


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