jerflash

iTrader: (1)

hey guys

my 89 bird has been running bad for some time now

idle stumbles bad from about 700 to 500 feels like it has a cam haha

burns gas like crazy

and it is much slower then it should be

not throughing any codes



tested: for vacum leaks with propane and found none

changed: IAC, cap,rotor, wires, plugs, coil, distributer

adjusted: timeing, tps, iac

i was thinging maybe the MAF but not sure
i have to barrow one from a buddy to see

help me guys is there anything that i missed doing???

thanks

89V6FBIRD

Leaky injectors? Put a fuel pressure gauge on the rail and turn the car to On but not Run and let the pump prime. Then turn the key to off and watch the gauge. If it drops to zero, its leaking somewhere there.

Vader

Have you checked/replaced the O² sensor lately?

If you had a MAF out of range, the ECM would let you know within 600mS of the error. It's pretty fast.

jerflash

iTrader: (1)

of i forgot to add that i changed the O2 sensor

it was running so rich it was fouling plugs but that problem was solved

i know that it may not be the maf but i heard from a few placed that a bad maf does not always through codes but thats why i have not baught one yet


the fuel pressure and leaky injector idea seems like a good one

they are very old

i was thinging that the diafram in the FPR was busted

so i might get a new adjustable one and a fuel pressure gauge and clean the injestors while im in there


thanks for the input but does anyone else have any more ideas about what it could be?

thanks

Red Devil

Check the CTS?

jerflash

iTrader: (1)

what is the cts???

89RsPower!

any fuel pressure readings? as far as the maf have you tried unplugging it and driving the car? If it runs better with the maf unplugged its most likely the culprate..

jerflash

iTrader: (1)

i need to pick up a gauge

when i unplug the maf it stalls all together

does that mean anything?

Red Devil

coolant temperature sensor. The MAF relays are cheap PM. pull the vac line going form the FPR to the plenum and see if there is gas there. If it's running that rich, I doubt it is a pressure problem (unless you have an AFPR).

jerflash

iTrader: (1)

i pulled the vac line from the FPR and it did smell like gas

see my problem is the only code shown when i read them is code 12 which mean the computer is ok

would a bad CTS cause it to stumble that bad and would it through a code?

and wouldnt the maf relays through codes?

i just which my car would tell me whats wrong haha

Red Devil

I don't, those same systems can and have been designed to tell the feds when you screw aroung with your car.

Most times they won't throw a code, but the MAF stuff has the best chance of doing so.

If the CTS is bad, it could report an abnormally low temp and the ecu would compensate by enriching the fuel mixture.

jerflash

iTrader: (1)

i agree with you there man

im going to meet up with a friend of mine tomarrow and i will swap the maf and see if that is the problem

i hope it is so i can just go and buy a weels unit already and if its not i will pick up some maf relays and see if that changes anything

we shall see

thanks for you help guys

if anyone has any other input please say so

Vader

Backing up a step or two, since you set th eTPS, what was the final voltage at the closed throttle position?

Since you have a DMM to set the TPS, you should be able to test the CTS:



And you can use that same meter to analyze the MAF power and signal circuits:



Or simply measure the MAF output at a given RPM:

jerflash

iTrader: (1)

thanks for the info, pictures, and diagrams vader

i have also thought that maybe it was the setting of the tps when closed that was causing my problems but i tried the .54 seting and alot of other and it did not make any diff in idle


inorder to read the maf output i have to put to positive term or the dvm on the signal out and the other to a ground right?

and those reading thats you showed are the normal readings at those rpms?




thanks again man this sould help alot

jerflash

iTrader: (1)

ok i did some checking of relays and testing of sensors

maf burnoff and maf power relays are both working fine


i could not get a reading on the coolent temp because of how it is set up

it would be easier to get a pigtail and mesure it but i might get a new one anyway

so i moved on to mesuring the maf output voltage and when i inspected the wires i noticed that all the wires going to the maf except for the signal wire were at one time cut into to test for voltage and were never taped back up afterwards

a real hack mechanice worked on this car at one time it looks like so i thought i found the problem i have been looking for but it was not because all the wires wer still working fine so i taped them all up

so i moved on to testing it
it is the original unit with the screeens removed(i know thats bad but i did it 4 years ago when i did not know anybetter)
with the car at about 190 deg. 800 rpm and the filter on it read around the 0.670 area but it would bounce up to like 0.700 when it went to 900 rpm

when i would rev the car the voltage would go up in as it was pulling more air which makes sence

when i put it in drive and it was at about 600 rpm it would read the same 0.670

but when it was idling the voltage bouncing all over the place. i dont know it it is because of the idle bouning up and pulling more air or if the boucing of the voltage was the reason for the idle surging??

i spent 2 hours checking and rechecking everything and im still at a loss

so you guys think i sould start looking at the fuel system?

jerflash

iTrader: (1)

an update to my problem

i ordered the hypertech fuel pressure gauge and the holley afpr from jegs and just got it today

i thought my fpr was bad and my injectors were leaking

so i hooked the the gauge and started the car and it read 35 then unhooked the vac line and it was at 46 lbs then hooked it back up and when i reved it it went back up to 46

then i taped it to the windsheld and started driving and got on it and it never went below 46

so i went home and tured it off to check if would bleed off fast but it stayed at 44lbs while i was looking at it but after 20 mins it went to 40 lbs

is this normal drop or no?

i will check it in an hour again

thanks

jerflash

iTrader: (1)

ok checked it 1 hour and 15 mins after shutdown and it was at 24 lbs from the 44lbs at shutdown


what does that sound like?

thanks alot

joe