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Sun Jun 18, 2006 2:53 pm

i recently purchased a 71 squareback. the people i purchased it from were honest and informed me that once the engine heated up there was a significant hesitation. can anyone help me and tell what the causes could be?

Sun Jun 18, 2006 4:00 pm

Could be dozens of things. If it is worse when warm then it is likely mixture related. But to implicate the EFI (and identify what component is bad), you must tune it (valves, timing), and eliminate ALL sources of vacuum leaks first. Many problems turn out to be either leaks or non-EFI related (often after spending $$$ for unneeded replacement parts). So tune it and spend an afternoon replacing hoses and checking all leaks, THEN see how bad it is.

Sun Jun 18, 2006 5:24 pm

You don't say whether it is still stock Fuel Injection, or has been converted to some type of carberator set up.
This makes a big difference in online trouble shooting.

Sun Jun 18, 2006 6:13 pm

this website is awesome! you guys replied quick as heck!....

ok, sorry i forgot something....lol

it is a stock fuel injection system... and the previous owner informed me that they had tuned it up just recently

Sun Jun 18, 2006 8:40 pm

Check the charging system. The Fuel Injection likes a constant voltage 13.5-14.5V into a fully charged battery. Low voltage will cause the fuel system to run rich.
Also, check the fuel pressure. 28-30 psi.
Check the distributor operation. Does the vacuum advance and the mechanical advance work properly.
In my almost 40 years of working on these FI systems, 90% of the time the problem is not in the FI system itself.

Mon Jun 19, 2006 4:10 am

ok.so pretend im an idiot...lol

how would i check the items you suggested?

Mon Jun 19, 2006 9:57 am

Buy the Muir "Idiot" book for starters, and read the engine and fuel sections through. And replace all hoses to be sure connections are tight (no air leaks). Tuning is FAR more important, so don't take the POs word--learn how to do it yourself and KNOW

Stick or auto?

Fri Jun 23, 2006 9:25 pm

ok so i was misinformed. it hesitates soon after you start the car. in addition once i have been driving i can press the accelerator all the way to the floor and it does nothing. then after a few seconds it will all of a sudden get gas and go..........this is so frustrating!!!!!!!!!!!

Fri Jun 23, 2006 9:26 pm

Sounds like the throttle valve switch. Does it act like a carb with no accel pump?

Sun Jun 25, 2006 11:50 am

yep.could that also be why it hesitates?

Sun Jun 25, 2006 1:50 pm

With the key turned on, but the engine not started, from the engine compartment, operate the throttle by hand slowly. You should hear 20 clicks from the injectors. If not, you throttle valve switch is bad, the wiring to it is bad.

Sun Jun 25, 2006 2:56 pm

i will definately try it. could this be the cause of the hesitation

Wed Jun 28, 2006 6:17 pm

ok i checked the throttle switch valve and it clicked all 20 times.

Wed Jun 28, 2006 6:52 pm

Another guess would be that the PO might have tried to "fix" the MPS by attempting adjustment. That could foul up part and full load without necessarily ruining the idle. Is there a (mostly clear) hardened plastic covering over the big screw head on one end? Or did a PO remove it to adjust it?

Another simple idea... check the distributor vacuum advance. It may not be EFI at all.

Thu Jun 29, 2006 9:51 am

Yet aNOTHer possibility, especially if the idle is a little rough, is that someone switched a pair of injector connectors at some point. It will run, but the timing of the pulses will be wrong and it will run rough, especially under load.

Thu Jun 29, 2006 6:02 pm

so how can i fix that? by the way i took your advice and bought the muir book.thanks! it explains things really well

Thu Jun 29, 2006 6:42 pm

Russ Wolfe wrote: With the key turned on, but the engine not started, from the engine compartment, operate the throttle by hand slowly. You should hear 20 clicks from the injectors. If not, you throttle valve switch is bad, the wiring to it is bad.

Hey Russ, is it supposed to click on all 4 injectors when you twiddle the throttle?

Thu Jun 29, 2006 8:06 pm

IIRC, it is just the 2 that are active according to which trigger points contact is closed.
This "feature" is a kind of FI accelerator pump.

Thu Jun 29, 2006 8:29 pm

That's what I figured.

Thu Jun 29, 2006 8:40 pm

If your injector connectors still have the plastic boots on them, make sure the black ones are in front (front is FRONT OF CAR, as Muir says), the grey ones to the rear of the car.