83 ur-q running problems

[Dave Lawson <dlawson@digitalglobe.com>]

Fred,

>Having a problem with 1983 ur coupe (vinxxxx594). Recently installed MC 
>engine (wx had 5 bad exh.mfld bolts,scored cylinder #3, non oem head 
>gasket, bad turbo etc. etc.) in short "NIGHTMARE". Used all original 
>injection parts etc. swapped wg spring and cap (black spring). Opened up 
>FTCU,looks un mollested. Installed ABT aux three gauge panel and vdo 
>gauges,(water temp, oil pressure, boost/vacuum).Engine runs strong but 
>will not even get close to red line. Boost is 13 psi, max rpm 5200. just 
>flattens out. Feels like something occurs about 4500/4600 rpm. I have 
>installed warning light in parallel with fuel pump power feed, does not 
>cut out. Checked air temp. sensor cuircuit (ok), coolant temp sensor 
>(ok). Some times the duty cycle reading does not fluctuate, stays steady 
>at 46%. If I rev engine a little ossilation starts. Frequency valve seems 
>ok, oxy sensor checks out. Need help with this. Thanks.
>1983 ur quattro cp, helios blu,BBS RS,Eibach/Boge.
>1983 ur quattro cp, alpine wh,H&R,Bilstein,TAP bushings,BBS RA 225/50/16

I would start by clarifiying your setup. BTW, I also installed and early 89 
MC engine into my 83 ur-q complete with the full engine control setup.
The questions I have are:
-What do you mean by flattens out? I assume you are not describing
a fuel pump cutout scenario? The engine is still running but falls on
it's face and can't exceed 5200rpm?
-What is you setup? MC engine but with 83 fuel system? What about
the ECU and engine control MC or WX? Which wastegate is installed, 
the MC or WX? You must have a modified ECU to get 13 psi with either
system. Which one?
-The freq valve duty cycle should fluctuate, except under WOT condition.

Also check the camshaft timing. I advanced my camshaft 1 tooth this 
past weekend (thanks PDQSHIP) and it definately changes things. The 
engine pulls strong from lower rpms, say 2200, but really flattens out
above 4700-5000.

>this AM,33 deg.f, rpms fine. 6,500 no problem. as eng temp increased rpm 
>limit decreasd. inlet air temp sensor wireing and sensor resistance check 
>out fine statically. cant afford to move to the yukon right now. would 
>much rather fix it.

Sounds like a sensor type problem. Oh, where did you get your water temp 
signal for the gauge you mounted? It's a problem if you doubled up on the 
temp sensor at the front of the head. The ECU uses this guy for coolant temp
and also hooking it up to a gauge will ground the signal through the gauge, the
ECU always thinks the engine is cold and sets the freq valve duty cycle to a 
constant value. The above is for the WX engine control.

This one could use some more info to help the diagnosis.
-
Dave Lawson  dlawson@digitalglobe.com
83 ur-q, lhasa green, 89 MC engine, eibached, bilsteined, and soon to be chipped
86 GT, graphite