synesthete

My car is '88 GXL

So i was having a problem with a pulsating drone coming from the exaust at light throttle.
Some helpfull forum members said check the TPS.

I adjust the TPS with the multimeter to 1.0: Now the pulsing seems less but still there.

I unplug the BAC connector: No improvement but idles at 500 Thats not right... Time to check idle.

I jumper initial set connector and using a tack i adjust the Idle mixture to max rpm, which happens to be all the way counterclockwise and about 550rpm.

Now i adjust the idle speed and can not get her to idle any higher than ~600. The adjust screw comes up but past a certain point there is no change in rpm. I cant get anywhere close to 750.

With BAC (jumper removed) idle is fine at ~750.

Anyone have any ideas they wish to share with my noob self, including mistakes i could have made (I am nub like that but not completely brain dead)??? I still need to check water temp and o2 sensors could either of these be the culprit?

Alex6969

i don't know what sort of tune ups or mods you've done so here it goes

fuel filter? thats what im replacing. if it doesn't do it, oh well its part of the tune up process that needs to be done. also plugs and wires.

my idle bounces from 780 to 500. and when i let off the gas from driving (say coasting w/ the clutch) it will drop to almost ~300 then pop up to the 500-780 marks

misterstyx69

iTrader: (142)

are you adjusting the TPS when the engine is fully warmed up?..my idle bounces once in a blue moon ..i adjust both the idle and tps when warm..she purrs at 750-800..i can bring it steady upwards to 1000 if need be,.but 750 -900 is the #'s mine likes the most,,depends on the car..seems every car has a personality of it's own..

synesthete

Yeah i set TPS after driving for a bit, so it was warm, everything off, key at on.

I can make idle go down and stall the car but i cant get it over 550-600 with the jumper in. The screw goes up to a point and then turning it more yields no change. With the jumper out (BAC working) it idles solid at 750.

swiftfc

please can some1 give me a write up on how to adjust the TPS? And dont say I havent search cuz i've typed everything for "TPS adjusting" to "How to adjust TPS" and so on if not a link can some1 give me searching tips?

synesthete

http://www.teamfc3s.org/main/factory_service_manual/

Chapter 4.

Chuck

iTrader: (2)

Instead of adjusting the TPS by voltage, try adjusting it by resistance. Get the setting to 1000 ohms. Then go back and run through the idle setting procedure with the initial set connector jumped. Have you checked for vacuum leaks? They can sure play hell with idle. Have you checked and adjusted the engine timing? Idle issues can be some of the toughest to find and correct on these cars!

swiftfc

thnx guys i must of skipped ch. 4

synesthete

Ok, my idle problem is fixed.
The plates in the TB were indeed out of spec.

The pulsing from the exhaust is still there though.

I got new plugs/wires/water thermo on the way.

Im thinking i should replace the o2 sensor as well as this sucker may be original.
Since from what i understand the o2 sensor adjusts afr at light throttle right?

Could the o2 sensor be causing my pulsing exaust sound while cruising down the freeway?