90 tracker hesitates when accelerating

[bcbud]

One problem after the other on this one.......when the engine is cold it accelerates fine without any issues for about 5 minutes. Once its warm, it hesitates so bad when accelerating that i dont want to even drive it. I changed temperature control valve but it did nothing......?

[fixkick]

90 , ever set the VR gap, or it can be a bad dizzy.
this car has stand alone dizzy, makes all its own spark.
i an extra vacuum line to cab and to a propane tank
if if it misfires, i add propane, if it clear up, it was lean if no change bad spark,.

hesitates or bogs.
bogs then catched up. or deep endless bog
hesitates, is this mifire? you can feel it, does it misfire? or just bog.
if its gross misfire, id bet the dizzy is bad, (tune it up and set the VR gap)
if it catches up. that bog, then the TPS is bad.

the TPS ,cause (bad) a bog, for 1 or 2 seconds, then catches, up.
called a TIP IN bog. The bog is corrected when the naturally slow map sensor wakes up (see reality) the added propane at bog will make it better.
the TPS is hard to test, they get old
the carbon ring inside wears out. and fails to send the signal to cause TIP IN enrich mode.
find out if its spark or fuel
then work that.
it can be hard to do that. (add fuel is one trick)

[bcbud]

It bogs then catches up but only when warm. When its cold, no problems. What is VR gap?

[fixkick]

when cold, the EFI is super rich already (maybe 10:1 AFR) (like a CARB choke) (the ECT shows hot and ECU enters hot running air mix mode)

when hot: THE EFI in closed loop (@14.7:1 AFR) and you hit the throttle hard, (this is huge air added fast) AFR = air fuel ratio.
the air flow is instant, and a huge air slug (hits the intake valves) and the result is a temporary bog . a gross hesitation. (TPS dead)

Enter the TPS:
the TPS senses this fast change (throttle angle) (virtually instantly) and causes the ECU to go to enrich mode , until such time, as the MAP senses this new air flow caused by driver, correcting this bad air/fuel mix.

This works just like the High-speed Accelerator pump on old Carb's and for exactly the same reasons. (that funny device that squirts, even key off.)
on carbs, the air is faster than the fuel (jets) (air is faster than viscous gasoline)
on EFI the AIR is faster than the MAP. (MAF in 16v) (or your right foot is faster than any MAP) can be... (move R.foot slower, see it work ok?)

This comment assumes good fuel pressure 30PSI, and ECU has good inputs .
Are the advancing weights working in the old funky dizzy?, (mech. monster)? they rust and fail just like all cars did ,back when.
Is the dizzy advancing correctly (full RPM advance) with a timing light attached? 18deg. on weights. alone.
8 static, +15 with weights, to about 23deg.? and the vacuum part works too, for 5 more degrees? (and the diaphram in the vac, adv. is not leaking?)
is the vacuum advance working ?

VR gap. open dizzy. see magnetic, coil (figure 1, id 5/6)
http://www.fixkick.com/IGN_timing/89-timing.html

The Vacuum advance, can be tested separately , pull hose and attach any hand vacuum pump to it it and check leak down first. (zero for 1min) and
then pump it and see the effect on advance, if no effect at all its DEAD.

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for sure spark is first, it must advance correctly or the fuel will not be burned fully.