[dongatta]

Hey all I have a 1986 D-21 with a FI 2.4L. When coming to a stop I push the clutch in and the idle drops like it wants to cut off then idles rough for a few seconds then back to normal. I have new 02 sensor coolant temp sensor thermo wax kit cleaned MAF ecu says throttle / idle switch. Went to the junk yard got a TPS and still same thing. Any help in the right direction would be greatly appreciated

 

[brookwood61]

Check your brake booster to see if it has a vacuum leak.Good Luck

 

[dongatta]

New brake booster and master cylinder

 

[zanegrey]

check all vacumn and check the bpt valve..it it the one right b4 the egr valve..

also check the fuel pressure regualator vacumn..some time moving it to a manifold source solves this prob..

 

[dongatta]

Thanks for your reply.if you dont mind me asking what is the bpt valve and if you are facing the throttle body which side is it on.I have checked all vacuum lines numerous times.If i route the fuel pressure regulator to a manifold source what do I do with the ends that is coming out of the top of the throttle body going to the fuel pressure regulator.Again thanks for any help you offer.

 

[zanegrey]

just in back of the tbi .. it almost looks like a flying saucer ..

cap it..

 

[dongatta]

ok thanks what am i checking the bpt valve for and I will re-route the vacuum this evening and post back

 

[zanegrey]

i am a little tired ...

so my first reponse to you should have been to try a tune up..

plugs wires cap and rotor fuel filter air filter and breather elemet.

even an oil change ...

 

[dongatta]

Ok here is a list of all i have done thus far
Nissan Wires - NGK Plugs
Distributor - Cap - Rotor Button
Set Timing
Compression Test
Thermostat - Heater Core
Engine Coolant sensor - To the computer
New fuel filter
TBI cleaned
New TBI gaskets
FI filters & o-rings
Used TPS per Vehicle computer
What am I checking on the BTP

 

[zanegrey]

check the bpt for operation.

with the truck running (you might have to idle it up for this )

pull the vacumn for the bpt ..note the effect..

put vacumn back on and pull the otherside vacum not e the effect ..and is the vacumn coming staight thru..

also check egr function..

 

[dongatta]

Thanks I will check what you have listed and post back later on

 

[dongatta]

Pulled vacuum on top of bpt engine ran rough pulled lower vacuum no effect. No difference when hooking up the fuel pressure regulator to manifold

 

[zanegrey]

check the bat cables for looseness and or corrosion..

check all the way down to starter..

also check belts for looseness

 

[dongatta]

Will do I am at my witts end on this truck

 

[zanegrey]

you removed your old tps..??

how did you determine how to put it back on..??

what positon did you set it at.. ??
this might just be the tps is slightly out of line...

 

[dongatta]

I just pulled it off the TBI and placed the other one on. I lined the old screw marks up on the one from the junk yard and tightrned it down

 

[zanegrey]

you noticed it has oblong screw holes..

it can be adjusted..

there is a proceedure..but try lossenening the screws just enough so you can tap the tps toward the longer part of the oblong..

just a tap ..do not get crazy and move it too far..

then start and test its idle problem ..

do it a couple of times to see if it helps..

 

[dongatta]

I want to say thanks for your time trying to help me get this truck rite. I had heard of a procedure of adjusting the TPS but I am far from a mechanic. I did notice the oblong screw holes. Should I take the TBI off to adjust the tPS or can it be done on the truck. There is only about a quarter inch adjustment either way correct.

 

[zanegrey]

do not remove the tps ..

you only want it to move a fraction..

that is whay i saw to tap once retighten .check idle and then repeat if neccesary

 

[dongatta]

Ok I will try when I get home. Truck is parked in the garage didn't drive today hoping to get the problem fixed. Post back later