Accerleration problem

A

Alpacamarc

New member
I have a '98 V6 5-speed, under load & full throttle it misses and feel like it's not firing on all cylinders (low on power as a result). This happens between 1k rpm and 2k rpm when at low speeds and in 3-4-5 gears (let's say you didn't feel like down shifting and just went WOT) it bucks pretty good then. It then always accelerates normally between 2k - 3k rpm, then at 3k it starts up again... not bucking like at the lower rpm range but rough (intermittently at first) and low on power. I had a mechanic drive it (my father-in-law) and he said it feels like it's not getting the fuel it needs. I have the receipts from the previous owner's attempts at chasing this gremlin, he recently replaced the following:
-spark plugs
-spark plug wires
-fuel pump
-fuel filter
-injectors (I think? Can't remember)

Anyhow, he was unsuccessful at fixing it and now I'd like to figure this out. Does anybody have any ideas? My next step is to buy a new (or working) coil and do a trial & error on the 3 coils to see if one of them is the culprit. If that doesn't do it then what... maybe a crank position sensor or some other sensor (??). After that I don't know... maybe valve-train (sticking valve, etc. ?). Thanks for any help guys.

,Marc
 
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No CEL I assume? A MAF sensor and TB cleaning wouldn't hurt and it's cheap+easy. I would test the MAF specs while it's out. I have heard of similar symptoms from a bad TPS too
 
I would think it would have cels all over the place if it was the ignition system.....

Have you tested the MAF, TPS, coolant temp sensor, cam and crank sensor?
What about pulling the timing cover and making sure the belt is where it should be?

Did he do his own timing belt?
A Toyota tech told me the piece that the crank sensor reads off of can easily be damaged by inexperienced DIY'ers and will end up with something like this.....
 
004Gunner said:
No CEL I assume? A MAF sensor and TB cleaning wouldn't hurt and it's cheap+easy. I would test the MAF specs while it's out. I have heard of similar symptoms from a bad TPS too
Click to expand...


can u link a good TB cleaning thread? last time i followed this one thread on here i think and it wasnt through (someone posted back and said that the thread i followed did not do a full job but rather hack job, i was suppose to take off the TB face or some sort , i just took off the intake box)

thanks
 
Thanks for the replies guys! Maybe some day, when I'm not standing on my head busy, I'll get a chance to try these suggestions.

JohnsD90 said:
Cool, i have this problem too, nice, ill clean the MAF soon.
Click to expand...

Good luck. If you don't mind could you let me know how it went and if it helped at all... would be much appreciated.

,Marc
 
SUCCESS! This is the trial & error history for chasing this gremlin.

Toyota dealership in Quebec were unsuccessful, they tried the following:

-new fuel filter
-new oil pressure switch
-new spark plugs
-new spark plug cables

I was unsuccessful with the following cheap fix attempts:

-cleaned the MAF
-cleaned the TB
-cleaned all the electrical connectors I could get my hands on
-checked all the vacuum lines for cracks, clipped the rotten ends of those that were starting to split
-new PCV valve

Finally decided to take a chance on the coils, went to the stealership and picked up a new one. I switched out the back coil first and VOILA... no more missing & chugging. I now love my T4R again!
 
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