Q 45 1991 My mechanic is stumped we did evertything once it warms a little yuk.

[kellychud]

this car has 95,000 miles of grandma. The car starts and idles ok then as it warms up it just gets progresively worse no power stalls wont rev past 4000. seems to shift ok. Knock sensors test ok, scans ok no codes changed computer no codes. changed platinum plugs one coil fixed all oil leaks etc like new now. Fuel pump tested while driving, nothing shows a problem, compression everthing very good wondering what to try next my mechanic is stumped.

[Q45tech]

Use a Consult to data log the important parameters rpm, coolant temp, injector pulse width, maf voltage, ignition advance then compare them to your file of good running Q in EXACTLY the same acceleration rate on the same coarse.

The point is an experienced technican who works on Q of that exact year every week will almost be able to touch the hood and come up with an accurate diagnosis.

After 20 years of Q45 availablity there is NOTHING new that hasn't been seen MANY TIMES before.

Failure to find or train your own MASTER TECHNICAN for your car can result in lots of false starts and wasted money.

Reading a 100,000 posts [skim many] is a good start.

Without WOT rpm vs MAF voltage graph [1.2 volts > 4.3 volts: rpm]Ignition advance vs rpm [15> 20>28]TPS votage [0.44>3.8 minimum]Fuel pressure [34> 43.4 psi].Voltage report from ecu [12.8 minimum running]

What does engine read in a chassis dyno test?

Need a massive amount of ACCURATE DATA to diagnose over INET more than most can collect.

Unfortunately what one mechanic thinks is ok many not be? It varies.

Precise exact accurate numbers PLEASE.