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Topic: 88 XR7 problems (Read 1201 times) previous topic - next topic

88 XR7 problems

My 88 xr7 had a bad miss in it in normal driving but when i mash the gas it goes away what could it be??

88 XR7 problems

Reply #1
Does it miss when the engine is under a load (sitting at a red light and in gear)? Do you have a check engine light?

It could be several things; from a vacuum leak to an ignition or fuel issue. We could use more information.
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88 XR7 problems

Reply #2
pull your codes,
use a paper clip

click on my diy link for the instructions and complete code list.

start with codes (click on my diy link below,,its kinda hunt an peck)
next, possible TFI module on the distributor or the stator assembly down "inside" the distributor (codes may tell you this)
next, with engine off and key on, prob the green wire to verify the tps has less than a volt.  SLOWLY** move the trottle open and verify the voltage increases evenly (this is "seen" best with an buttstuffog meter) because you can see any intermittant open areas in the variable resistor. (codes should tell you this)
next fuel presure (needs to be about 38-40psi at idle with vac line on regulator) (needs to be about 42psi with vac line on regulator plugged off)
next if there is wetness in the fuel presure regulator vac line, faulty regulator diaphram so change it.
next spark (needs to be blueish white). Spray a water bottle along plug wires at night to look for arching in the air
next vac leaks (spray carb cleaner in / along vac connections as well as intake and listen for idle change)
next, egr system is clogged full of carbon such, codes may tell you the eVP sensor is not responding.
next, compression test all cylinders after you started it up soaked up the cylinders with oil,,takes only a 10 or so second run time.

so yeah,,
theres lots to look at but start off with a basic tune up first which will set you back 150.00 in materials right off the bat if you cant recall doing one.

88 XR7 problems

Reply #3
pull your codes,
use a paper clip

click on my diy link for the instructions and complete code list.

start with codes (click on my diy link below,,its kinda hunt an peck)
next, possible TFI module on the distributor or the stator assembly down "inside" the distributor (codes may tell you this)
next, with engine off and key on, prob the green wire to verify the tps has less than a volt.  SLOWLY** move the trottle open and verify the voltage increases evenly (this is "seen" best with an buttstuffog meter) because you can see any intermittant open areas in the variable resistor. (codes should tell you this)
next fuel presure (needs to be about 38-40psi at idle with vac line on regulator) (needs to be about 42psi with vac line on regulator plugged off)
next if there is wetness in the fuel presure regulator vac line, faulty regulator diaphram so change it.
next spark (needs to be blueish white). Spray a water bottle along plug wires at night to look for arching in the air
next vac leaks (spray carb cleaner in / along vac connections as well as intake and listen for idle change)
next, egr system is clogged full of carbon such, codes may tell you the eVP sensor is not responding.
next, compression test all cylinders after you started it up soaked up the cylinders with oil,,takes only a 10 or so second run time.

so yeah,,
theres lots to look at but start off with a basic tune up first which will set you back 150.00 in materials right off the bat if you cant recall doing one.

88 XR7 problems

Reply #4
Quote from: creekcougar1988;406993
My 88 xr7 had a bad miss in it in normal driving but when i mash the gas it goes away what could it be??

 The car wont start the first time usually takes three cranks, put it in gear and start down the road cold, goes about a mile then starts
missing pretty bad i can step on the gas and the miss stops then after you drive a little bit it all goes away, till you stop go in the store or something, drive it about a mile then it starts again. Had plugs and wires 6mo ago and new coil, and battery. The car has some mods, gt mustang upper intake, throttle body, underdrive pulleys thats all in the motor. Has a 90 mustang gt aod tranny with shift kit.

88 XR7 problems

Reply #5
Look over the grounds

88 XR7 problems

Reply #6
Verify fuel pressure.
-Cycle key on, watch for pressure to be at least 35psi, shut the key off.  You want it to hold that pressure for several minutes
-Start the engine, you wan't to see 35-38 psi at idle, and as much as 45 psi when you snap the throttle.

If either of these tests fails, you need to investigate your fuel delivery system.

88 XR7 problems

Reply #7
fuel filter replaced lately?