94 Q with 125k, new fuel pump but still seems hesitant

[aliciaford]

Ok, so I sold the 1990 Q and thought I had better do a major service to the 94 Q before I make her my daily driver. So, lessons learned with the 1990, I changed the fuel pump, and fuel filter. Changed coolant, belts, thermostat and water pump. Had transmission serviced and changed oil, cleaned MAF and throttle body. The car still has a some hesitation when accelerating. I have tried to figure out what the heck is going on. I bought new NGK plugs but havent installed them yet, thinking of installing new MAF at the same time. When do they "go bad"?

[Jesda]

Check the fuel injectors for proper resistance and examine the FPCU.

Not unusual for a MAF at this age of Q to go bad. When you got plugs, I hope you ordered the correct ones. The Q is really picky about that.

[aliciaford]

I bought the NGK PFR5G-11. Thats what my mechanic recommended, sound correct? Is it as common on the 94 for injectors to go bad? I had thought that the 94 was much more reliable year.

[Jesda]

Those are the correct plugs. Injector failure on 94-96 is known to happen, but less often.

Its not unusual to put in a new fuel pump and have the FPCU die shortly after.

[aliciaford]

How would you suggest checking for FPCU failure? I think I will install new plugs this weekend and then if I still have trouble go after the FPCU.. Probably a fortune for a new one... Thanks for the help!

[Jesda]

You can try the FPCU alligator clip trick to see if the hesitation goes away. If it smooths out with the clip there (which causes the pump to run at full pressure -- dont leave it like this) then you can probably suspect that the FPCU is the source of your trouble.

zerothread?id=73822

I suggest keeping a stash of used FPCUs just in case. Junkyards, unaware of how rare they are or what they cost new, just think they're generic electronic components and sometimes let them go for as little as $10.