06, 78000mi, 3.8

please help me.

ran for about 20 miles everthing perfect, idle, acceleration everything perfect. no engine light on. good exhaust coming out muffler. then it comes..car only max out at 20 miles an hour while rpms at 2500.

got it home. sat for 2 hrs. tried it again. perfect idle, not surging, hit the pedal to 4000 rpm running down road and speed moving forward was comensurating perfect the rpm. all good.

next day perfect again.

today--bad day. perfect, everything for about 20 plus miles. then repeated same thing as in paragraph one. the front brakes were extremely hot. could it be stuck caliper(s).

let sit two hours. everthing perfectly running again. what is the problem. what do i look for next time it does this.?

 

Define extremely hot.
Couple miles and one brake application and the rotors will burn the F outta your fingers.
So define extremely hot.

 

Thanks for the question and the response.

Right "hot" rather subjective as I new it was. I just couldn't come up with an actual temperature so i used "hot" as associated with a burning smell.. it would burn my fingers.

i am planning on getting it scanned later after doing more research. i don't know what else. i did a couple hours researching.

possibly the harness under the power steering reservoir. read and seen picture these vans on occasion have insulation break down and wires in the bundle begin touching one another. but symptoms describe don't appear to be mine as described on forum.

 

Brakes dragging can be an issue, the catalytic convertor will cause the issue you describe, but generally not intermittent.

Depending on how bad the brakes are dragging (if they are) it could be enough to drag the driveline down.

 

Thank you for response. Got back from having engine scanned. there are no codes. i ran it hard and still bad running did not come back.

i did put in in gear and with foot on brake ran it to 2000rpm and what i heard was a light pinging, as though poor gas. but that doesn't have anything to do with it. unless ping represents something else

Don't know what a drag line is?

I can't, I mean I don't want to try swapping parts. I am not working right now.
I thoght about changing egr valve. but engine idles perfect, no surging, no missing.

Can't see it being CAT, good exhaust out the rear end. good meaning no fluctuation, no smoke of any color.

 

Was wondering and thinking about my vans problem. Could a possibility be that the temperature sensor believes the van is overheating due to some fault? It then won't let the van accelerate any faster? Is you think so, is there a test to determine if it sensor is good? What is it?

I checked level of tranny fluid. It is perfect? i wonder if it could heat up because of hot temps in s. florida lately and expand the fluid to higher level then should be. the computer then might since over fill and only allow limp mode?

Anyone knowing anything about the shut down relay in fuse box under hood. i checked voltage and got good voltage on one of its leg. didn't know if i should get it to other legs. I kept relay out and engine still ran while in park.

 

Can you continue to drive for more than a mile or two when it's acting up? If the brakes were dragging enough to keep you at or under 20mph and 2500RPM in first gear you would be using a whole lot of the go pedal and after a mile or two the brakes would fade and you would be able to accelerate again (albeit irresponsibly since you would have no real braking power). Also, when you release the accelerator the van would come to a rather quick stop.

Since you didn't mention either of these I'd say the hot brakes, while interesting, are not the cause here. Perhaps after we get it running right they would be worth looking into.

It doesn't sound like the catalytic converter but it is hard to totally rule that one out.

Since your van is an 06 it should have the fuel injection harness routed out the passenger side of the engine instead of the driver's side. I've never seen that harness fail, only the one that runs out the driver's side and WAY too close to the exhaust.

You mentioned the engine won't rev above 2500rpm when it is giving you trouble and you are trying to drive. When it is in this state, what happens if you put it in neutral and try to rev it? Will it also stop at 2500RPM? That would rule out quite a lot of other things.

My thoughts are that it is something electric or engine control related - perhaps a sensor or ignition issue. Have you checked the spark plug wires? Perhaps the coils heat up and start to short internally?

When it won't rev above 2500, does it run up that far easily then act like there is a 2500rpm rev limiter, or does it start to lose power and slowly climb to 2500 as you stomp on the accelerator?
If you get it up to 2500rpm then lift off the pedal and convince it to upshift, can you get to that engine speed again in 2nd gear, or does it never shift?

 

Is the fluid in the master cylinder contaminated? Is the vacuum sucking brake fluid into the intake from the leak while your circuits are blocking the fluid from returning?

 

thank you both for your response and questions.

ntech--i do pull out fluid from brake master cyl. everytime i change oil. maybe 3 to 5 oz as much so that i keep fluid in the system, to avoid needing to get any air out of lines in case i withdrew too much. if you mean the vacuum into the brake booster. i will look for that. i guess i should do it when running, but the engine would start stumbling and maybe turn off.

ZER0 Lot of good questions, of which some i haven't made observations for my elderly mom was in the van with me on one of the two occasions and i was concerned with keeping her comforted and getting out of heavy traffic at the time. I will pay more attention next time. wish there was no next time.

Yes I can continue to drive after it starts acting up for a mile or two. i still could brake. i will rule them out for now. The CAT i thought i could rule that out since it is intermittent and no codes. NO?

As far as rev past 2500 rpm in neutral i will try later. I know when it is running good, i can't rev past 2500 when in park. Even if I go down now. I know for sure I can't I have tried in the past when i never had any problems. One person told me that some cars and vans are programmed not to allow that to happen. I thought I was one of them. If you have similar van, can you rev past 2500 in park?

Plug wires: I didn't think plug wires because it runs really well and idles without a miss. the wires and plugs were changed 25000 miles ago. and when problem occurs engine isn't missing. if you still believe that is an issue maybe, should i use a meter and give a continuity test?

Coil--Are you saying coil could be intermittent problem. But if i can go 2500 rpms then still could be coil? I wouldn't know how to test that issue. I can test by holding screw driver between plug wire and coil and observe spark. I saw that on youtube. But engine is running well, i believe good spark is apparent.

REV easily to 2500 rpm--don't remember--i believe it didn't get there smoothly but not sure. will observe

 

I don't think your engine is consuming brake fluid, if it was taking in enough to stop it at 2500rpm it would be smoking like crazy. I've seen brake fluid get into an engine once, it smokes a LOT.

I agree, not the cat. If it revs smoothly to 2500 in gear and refuses to shift I'd start thinking it's the ecu/pcm. And check for transmission codes, though I'm not sure what failure would keep it in first gear, limp mode would be second gear all the time.

If it starts missing and stumbling and will upshift if you lift then I'd vote for something sensor related.

Does changing the gear selector position have an effect? Interesting that it has the same rev limit in gear as it usually has in neutral.

Scrap my does it rev over 2500 in neutral question, I forgot the rev limit in neutral was 2500, I thought it was 4000.

Great caution is required when testing live ignition circuits, I'd hold off on that until we have a better reason to suspect that as the cause