Having weird power issues with my '88 2.9

[Xandor]

Im going to guess its the CAT. My 94 ranger is runnin wonky like that and my brother inlaw sold it to my after he replace all wires filters and o2s. I bought it because it has to be the CAT. havnet got aroung to cutting it out yet.

 

[holyford86]

The computer has three grounds in three different places, any one of them being bad could cause a driveability issue, Having a bad cat would not cause the engine to run better above 3k rpm, its going to lose power and run like a bag of crap the more throttle you feed it. Have you pulled codes? Have you tested your TPS? using an analog voltmeter and backprobing the center pin of the TPS while slowly opening the throttle with the key on engine off will tell you if it is bad, if the voltage levels out or drops while you are opening the throttle it's bad. How does the fuel pressure regulator look, is there gas running out of the vacuum line when it is removed from the intake with the engine running?

 

[DisturbedMXer8]

Nope, none of that stuff is bad. FPR is fine, so is my fuel pressure. TPS seems OK, although I'm going to try and scope it the next chance I get. My grounds are all fine. Last time I pulled codes I didn't get anything, but I'm going to try again soon, maybe now that it's a bit worse it will trip something.

 

[dock83]

Try unplugig your o2 sensor and run her like that or pick up a can of combustion chamber cleaner and clean you throttle bodie butterfly. I used a tooth brush then ran the engine and sprayed it into the intake cured my babies flue.

 

[DisturbedMXer8]

Already cleaned the throttle body, IAC, and intake manifold when I replaced my Distributor. Almost sparkly clean. Also, I know that unplugging my O2 will throw a light and piss my computer off, so I don't think that'd be the best of ideas, to be quite honest.

 

[dock83]

What about an exhaust restriction catalytic converter can cause weird problems after warm up and my buddie has been having similar trouble with his 2.9 and his result was a pluged muffler. Droped the exhaust from the cross over what a difference.Neighbours didn't like but you gotta do what you gotta do.

 

[IMenriched]

Already cleaned the throttle body, IAC, and intake manifold when I replaced my Distributor. Almost sparkly clean. Also, I know that unplugging my O2 will throw a light and piss my computer off, so I don't think that'd be the best of ideas, to be quite honest.

Still hints a small vacuum leak.....I had to go over my lines very carefully...even the rubber ones pinch & squeeze the entire length....I found a couple of areas that were soft, or softer than the rest of the line...combine that with the heat of the engine it might be enough to allow it to collapse....that or the vacuum booster for the brakes has a slow leak.

 

[DisturbedMXer8]

Ok, just discovered something.
This problem started happening right around the time I replaced my FPR. Before I figured out that it was bad, though, my truck wouldn't idle. So, I adjusted the throttle screw out a bit so that it'd stop dying at lights. I had no idea that it messed with the TP adjustment. After I fixed it, I moved it back to where it was before (or so I thought), which had me idling around 800 rpm. Could this be the source of my problems, maybe? It can't be that far off, but maybe it's just enough. The timing of the problem is definitely right.

 

[IMenriched]

Ok, just discovered something.
This problem started happening right around the time I replaced my FPR. Before I figured out that it was bad, though, my truck wouldn't idle. So, I adjusted the throttle screw out a bit so that it'd stop dying at lights. I had no idea that it messed with the TP adjustment. After I fixed it, I moved it back to where it was before (or so I thought), which had me idling around 800 rpm. Could this be the source of my problems, maybe? It can't be that far off, but maybe it's just enough. The timing of the problem is definitely right.

well I guess I understood you to have adjusted it properly...& it is not hard to do, no big deal. Just need a needle sweep multimeter. here is some good info.
http://www.fordfuelinjection.com/?p=30

get that right and go from there

 

[DisturbedMXer8]

Alrighty, I checked it and it was definitely off. Closed position was at about 1.1v. Not bad, but definitely over spec. So, I adjusted it down to a steady 0.93v, which is actually as low as it will go. Also, I don't have access to an analog volt meter, but I checked the TPS range with my DMM anyways (better than nothing), and it seems fine. Steadily rises from 0.93v at closed to about 4.5v or so at WOT (don't remember the exact number, but it was right about there). Everything seemed to be in spec, so I took her for a test drive. Here's what I noticed:

1) Lower idle. Now it sits around 750-850 RPM at idle, while before was 800-900. Still vibrates a bit though, probably an intermittent misfire.

2) When I start it up, it fires up to about 1500 RPM, back down to 500 (barely running), then the computer kicks in and brings it back up to 800 or so. It always dropped a bit before stabilizing out, but never that much.

3) Smoother shifting, oddly enough.

4) Still seems to lack power below 2.5-3k RPM, give or take. Still lacking in acceleration.

So, adjusting the throttle did help a bit, but it still seems to have the same basic problem. I'm going to get a scanner for it here soon, probably sometime next week. I'll scan it again in hopes of finding a code that I missed before. My road test today was a bit slower paced, unfortunately. It's raining here, and I'm in Southern California. Traffic right now is no faster than 55 on any freeway, so my only opportunity to really get on it was the on-ramp, and I was only able to make it up to 55 (which is where it gets real bad, usually). Like I said, though, judging by the slow accel and the sound of my engine, it seems my problem still persists.

 

[HndMeDnBroncoII]

have u looked at the accelerator cable under the pedal the cable stretches over time.so when you step on the pedal the first 1/4 to 1/2 inch isnt even moving the throttle plate
i noticed serious driveability improvement after that.

 

[Lee_533]

It sounds like it might be a bad fuel pump or filter. Also check cat and muffler to make sure they aren't plugging up. Does it ever do it right when you start your truck?

 

[DisturbedMXer8]

Well, to reiterate, my power loss is only below 3000 RPM. Once I hit 3k or so, it instantly cleans right up. I doubt that a bad fuel pump would make it better at higher engine speeds, I'd think quite the opposite actually =P.

So, update. Every now and then (usually when going from park to drive, or vise versa), my idle will drop for a few seconds and then the computer will correct it. The thing is, last night it did it again, but it died instead. I did adjust the throttle down quite a bit, but I know it isn't supposed to be quite this extreme. I am really losing it on this one, guys...

 

[HndMeDnBroncoII]

turn the screw back up set it at idle according to the engine tag that should correct that.did u check ur throttle cable

 

[DisturbedMXer8]

Ok, so I bought a Ford OBD1 scanner the other day and did a KOEO test on my truck. I got three codes:

O11
C11
10

O and C stand for On Demand and Continuous Memory (respectively) I assume. According to the DTC charts, code 11 means the system checks out ok. However, I have no idea what the 10 is. Maybe it has something to do with the scanner, not my truck. Either way, my Computer thinks everything is ok, and I still definitely have the problem.