I have a '95 Bronco with a 302 and AOD. Frequently, but intermittently, it loses power about 1 minute following starting the engine. The power loss lasts a minute or so, and then the power comes back. It doesn't miss, buck, ping, emit black smoke, or display any other symptoms. It just ignores the throttle. It does not flash a check engine light. It does sound slightly different out the exhaust when displaying this behavior. It emits a slightly tinny sound (I'm not sure how else to describe it - perhaps like stepping into the throttle on a carbureted car with the choke on?). It has 86k miles on it. It has been serviced by the book. The main engine computer has been replaced. I have checked for vacuum leaks everywhere I could think of, and found none. I have not replaced the oxygen sensor. It has been doing this for a couple years. No mechanic has been able to figure it out. Does anyone have any suggestions on what I might investigate?

 

Loses power as in does it stall or does it seem like your throttle linkage has become disconnected? A friends '93 would stall when he would lift his foot off the gas and put it back on and a new fuel pressure regulator solved that problem.

 

Almost sounds like your catalytic converter has a chunk broken off inside that falls over and blocks the exhaust. Could be another thing to check

 

OH MY GOD........... your actually worried about loosing power the FIRST MINUTE you have the truck started.

Serioulsy though that is NOT a problem. After you start the truck you supposed to let it run 3 minutes before driving. Your NOT supposed to start it up and floor it. Start it up and sit there for 3-4 minutes then drive away. Afterall what is 3-4 minutes over the lifetime of your engine. You do this and your engine will last alot longer. HOPE THIS HELPS!!

 

i would still have the codes pulled to see if possibly your evp or tps is working properly. this could give similar simptoms. do the rpms fluctuate at all?

 

Sorry, but I have to disagree. Your statements are true for carbureted engines, but not necessary with fuel injection. Its actually better to start driving right away because this will cause the engine to warm up more quickly. Cold engines don't get lubricated as well as warm engines. Getting it warm as quickly as possible will cause it to last longer.

Have you checked your codes? If so, post ALL codes that you retrieve and maybe we can provide more information.

 

Thank you all for your suggestions. To answer all the questions:

It does not stall. It continues to run smoothly, but won't accelerate. There are no codes stored in the computer. Do the RPM's fluctuate at all? Well, I have another oddity, which is also intermittent, and doesn't necessarily correlate with the original problem. That is, when I start the engine, sometimes it will jump up to about 1500 RPM, blink the check engine light twice (it doesn't set a code though), then bounce the RPM around as if it can't decide what to do. As soon as I put it in gear, idle returns to normal and it runs fine, unless it decides to have one of its power-loss episodes.

If I had a piece of catalytic converter broken off, I would hear it rattling around, wouldn't I?

Oh oh. I started a controversy. I believe in driving off without warming up the engine. I take it real easy until the engine is up to temperature. I have read that idling a cold engine causes unburned fuel to accumulate on the cylinder walls, which then displaces oil and leads to wear. Either way, I live in Arizona, so cold starts are not what they are in Minnesota.

 

Have you checked the TPS?

 

Is the TPS something I visually inspect, test somehow, or just replace? I have located it, but can't determine what I should do to check it (I'm an accountant, so cut me a little slack). The TPS looks like it can't cost a whole lot, so maybe I'll just replace it. Can't hurt, right? It sounds like a very good suggestion. Thanks.