surging and dies

[halofreek]

I have an automatic 1989 bronco 2 4x4 and I've been trying to fix this problem for over a year. After it warms up when I come to a stop the engine surges. Sometimes it dies and sometimes it fixes itself and starts to idle really high (like 1000 RPM). Also when its warm and I'm driving highway speeds it will sporadically jump up about 400 RPM and go back to normal. I have tried cruise control and it does the same thing.

What I've done: replaced the TPS, TFI, FPR, IAD valve, fuel filter, remote mounted the TFI, checked all fluids.

 

[Hagan]

Whats the fuel pressure? Do you have 1 fuel filter or 2?

 

[Nathan123]

My 89 does this exact same thing. I've just been fooling with the setscrew for the tps...it seems to be affected by weather conditions for me, maybe thats just coincidence? It real sketchy when you let off the gas to come to a stop or slow way down to make a 90 degree turn and it stalls and you dont notice it right away, but you notice you lost the power brakes and power steering. Sometimes I can get it to run okay then all of a sudden it goes back to surging then it'll take some fooling on that screw and it works good again...also going over a bump causes the surge for me. But you replaced the tps, so you'd think its not that.

 

[rangergi]

I have a 2.5l. While this may not be revelant to you, for me it was my tps, it had "low voltage" also while replacing the tps I replaced the iac and the spark plug wires. It was fine after that. Hope this helps.

 

[halofreek]

I just took the fuel pressure reading and it was about 30 PSI and today I finally got codes which were 41 and 95.
41 is exhaust gas oxygen(EGO) sensor: voltage signal always "lean" ( low value)- does not switch.
95 is Thermactor air system problem- right(passenger) side air flow always upstream. OR, Fuel pump monitor (FPM) signal- indicates circuit problem.
Does anyone know where the ground is for the fuel pump?

 

[Nathan123]

I think your best bet for the fuel pump ground is just tap into the ground wire in the harness (the color is in a haynes book) and just run your own wire to a good ground, then you know it has a good ground.

 

[halofreek]

I checked the pressure again when it was surging and dying and I noticed when it did that the pressure would go up to 40 PSI so I do not think it is a fuel problem. Any other suggestions?

 

[nodrog61]

i had a similar problem a few yrs ago with my 88 and it turned out to be the o2 sensor. you can find it on the exhaust on the pass side under the door.

 

[halofreek]

After replacing the computer and the MAF i still have the same problem. Today i went up to 75MPH and quickly slowed down the check engine light came on and the codes that popped were:
41 is exhaust gas oxygen(EGO) sensor: voltage signal always "lean" ( low value)- does not switch.
and 63 is Throttle Position Sensor (TPS) signal too low TPS.
I don't think it would be either of those since i have changed both several times already.
any ideas?

 

[halofreek]

and ideas?

 

[adsm08]

Wiring. You have a wiring issue. If all the components have been replaced and the problem is still there, you have a wiring issue.

 

[bfiakas]

I read that you remoted the TFI.How did you secured the 3 wires at the distributor and where they cut even when you did that part of the remoting.I had the middle wire at the dist. pop out just enough to cause a bad connection.As what adsm08 said check all your connections and do voltage check procedures as per your service manual if you have one.The TPS voltage should be between.90 to 1.0 volts

 

[halofreek]

My book says to check the voltage of the TPS, use a breakout box and test the voltage between terminals 89 and 90 and it should read 0.9V. Is there a way to check that voltage without getting a breakout box?