rough idling

hello guys, its been a while since the last time i'm at this site... need a little help from the TVT pros with my van. In park or neutral gear, idles fine but when put into drive, idling becomes rough... what are the things to check?

Check the air intake hose right at the throttle body. I think you got a hole. Most likely at that first "rib." Easy fix. Use a rubber cement, like GOOP, and wrap it several times with electrical tape.

thanks for the reply sir. i'll go check it out. i'll update the outcome

checked all air and vaccum hoses, no leaking found. what else could be the problem? any suggestions TVT's?

Does it cough or sputter when you try to get going?

no, van doesn't sputter nor cough. as you accelerate the rough idling fades away and then as you stop while still at drive gear, idling rough again. what do you think sir? what and where should i check?

Is it running like my Van is in this video? A bad lifter can cause a misfire but run totally fine on the highway.

http://www.youtube.com/watch?v=n-oUOs_0o2Y

thank you very much sir for that video but no, van doesn't run like that, as long its in nuetral or park, idles fine as soon as you put gear into drive, idling becomes rough. the engine still runs quiet, i don't have that "clang clung" (diesel-like) sound that i'm hearing from your video. any more ideas sir?

I agree with KC's 1st suggestion. It's really easy to miss a torn intake hose. Another way to check is to squeeze the hose while idling in neutral. If it's a bad hose squeezing it will cause the crack will open bigger & it will stumble or stall. The reason it runs bad while in gear is because the motor torques to one side causing the crack to open bigger. My money is on a cracked/torn intake hose. Tim

thank you sir tim. i'll try to thoroughly check again that hose. i'll update as soon as i'm finished checking

cold, warm, hot, or all 3?

after a thorough check of the big hose, no cracks found at any part of it. i did the squeeze test that you told me sir tim , the idling stayed fine only rpm drop happened. Hi sir RawbSpear, good question, the rough idling starts to soften when the engine is warm to hot or after a long drive. any more ideas sir?

Idle up temperature switch, and cold start timing switch. Posible temperature switch issue.

you said you experienced a change in idle when you squeezed the hose from the M.A.S. and the throttle body? That means there was a change that the computer tried to compensate for. ~~Triple, quadruple check the hose with a magnifying glass. NO LEAKS ARE ACCEPTABLE FROM M.A.S. (M.A.F.S.) TO THROTTLE BODY!

Have you checked the numbers coming from your M.A.S? are they correct? E.F.I. is the first problem in the fuel system.

@KCG: park your van till you have lots of money. Making me sad after i watched your video.

Quote:

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Originally Posted by RawbSpear

@KCG: park your van till you have lots of money. Making me sad after i watched your video.

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I replaced the bad lifter a long time ago. It runs very well now. I haven't been driving it now because it's not licensed, needs a new battery, and the back door latch is broken.

guys sorry for the late response, i've checked the three sensors on the rad, following the steps on the manaul, they are in good condition. what could else be the problem? as of now, the rough idling is still there though sometimes its fine. any more ideas what to other things to be checked? i'm really having a hard time making time for my van because i'm busy preparing for my wedding, we also plan to make van our wedding car.... thanks a lot guys... hoping for your help :)

you have good plugs, wires, cap and rotor right? good o2 sensor? clean air filter?

yes i have good plugs, wires, cap and rotor. good O2 sensors. clean air filter. i don't have any codes recorded at ecu. what else sir?

have you pulled off the throttle body and cleaned it?
checked all the numbers of the MAS?
good ground, strong battery?

the next step is testing fuel injectors and the air sensor. Top of motor comes off to get to all that. Look in the FI section of the manual and you will know what i am talking about.

ok i will check all of that... thank you very much... i'll update as soon as i have my time again

make sure to have a new throttle body gasket on hand for when you re-install it after cleaning.

while you have the throttle body off check the numbers on the T.P.S.(throttle position sensor). its pretty much guaranteed that this part is broken at 150k miles and needs to be replaced. Some of the pro's here say just to replace it if you have not already.