99 Tacoma pukes, gags at 2000 rpm

Ongoing problem. Runs great up to 2000 rpm, after which motor heaves, shakes, loses power. Back off to less than 2000 rpm and everything is normal. Have tried it all, including dealer. No solution. Fuel pressure good, pcv o.k., Cat conv o.k., replaced MAF sensor, timing belt o.k., plugs, plug wires and coils good/replaced, timing belt o.k., fuel pump new. No check engine lites on and no codes show. Help before I shoot my truck or myself.

 

I had a similar problem it wound up being a dead cell in the battery ive seen many things but never herd of a dead cell causing that but sure as shit soon as i replaced the battery it was back at 100 percent
That was on my 96 tacoma 2.7. It took me a week to figure that out and i found out by accident. Good luck hope i could help

 

Thanks for posting that up, Ive been troubleshooting basically the same problem, no codes. Took it to the Dealership, which I never do
and they had no clue. Easy to swap a battery to rule this out. Again Thanks

Have had 3 friends that are pretty good mechanics, along with myself, nobody has a clue, after checking basically every component
on this truck. we are stumped. I will be amazed if this is the problem, but the battery is kinda old, but seems to work ok. But looking close at the battery, it looks like by one of the cell there is a small melted spot, very small. wonder if its a dead cell.

 

Just check the voltage at the battery after it's sat for a bit. It should be around 12.6 volts. If it's low like 10.5 then you have a dead cell.

 

Just swapped out my battery, but reading your post, probably not the problem, battery seems to stay
charged pretty good, but I guess we will see. I will let you know what happens. The one I just put in is a brand new one.

When you really need the OBD2, it lets you down.

 

What engine?

 

Do you have an OBD scanner that can log data. The Torque App does.

 

So, did not help, its a 4.1 2RZ. You know I always read, Dont throw parts at a problem.
The OBD2 does not help, Toyota Service Tech had no Idea, which I find strange.
He basically said, its either the Dist or the Igniter ( and this was a total guess ) on his part.
Dist = 550.00
Igniter= 450.00
I always thought that Toyota Mechanics could figure it out, tho its my last place I want to go.
This is not so.
Its kinda hard to test the spark when your driving under load, which is the only time it happens.
And its not like its goes dead, total no spark, lets say it get 1/2 spark for say 1/2 sec. Kinda
for lack of better words, a Bump. I do have a FSM and have been testing everything I could test
everything comes up perfect, cleaned every connection on the truck, which were all clean to start with
So I guess it comes down to , either, Dist....Igniter.....Ecm, and these are expensive to throw money at
but what do you do.

Mechanicjon, I have a Atron scanner it does graph and saves, what would I be looking for, everything I see in the live data looks perfect

 

they make a stress tester for ignition sytems,

Automotive High Energy Ignition Spark Tester - Great for Testing No Spark Condition, Misfires or Check Engine Light with a Misfire Code

https://www.amazon.com/Automotive-Energy-Ignition-Spark-Tester/dp/B01MAT7UMW

loosen the exhaust before the first convertor and take her for a run to "verify" that this isnt an partially plugged exhaust.

scan the for sale adds on this site and see who has a used distributor/igniter that they are willing to part with reasonably.

 

While under the hood, I happen to look down at the Alternator, Hey another plug I havent checked yet
Had a hard time removing it, but it finally gave up its position it had held for 23 years. Full of Corrosion
I had not found any in all the connections I had looked at. I cleaned out with electrical spray cleaner
Going to let it dry out over nite, snap together in the morning and go for a drive. I have tried to find a
wiring diagram , to see what those 3 wires feed to, so far no luck. If they have anything to do with the Ign
I might have just found my problem. Hope, Hope. When you have a strange problem with your truck, you
Learn alot.
I have one of those stress testers, but have to admit didnt know it was a stress
tester, thought it was to see if you have spark, problem is mine only goes crazy under load, I can rev it up in the garage and it sounds great.

 

Took it for a ride this morning, really thought that plug would have been causing it.
Same problem, got under truck with my laser heat gun, 285 before the cat
295 after the cat, truck was idling, basically the same before and after Muffler.
dont think its a semi plugged exhaust system.
Darn I thought I had it.

 

Get an adapter at the part store and check your fuel pressure. Also have a look at your harmonic balancer and see if it wobbles, and is lined up with your other pulleys. The crank pulley will walk on you sometime if it's not properly torqued after a timing belt install. (causing your crank sensor to not read properly)

 

I installed a nice fuel pressure gauge, everything pressure wise is great.
Harmonic balancer is straight, I had to find my timing mark, and check my timing, so I
had alot of "alone time" with the balancer Timing was perfect, didnt drift around. (much)

I have a used Igniter coming (wish it would get here). I have a brand new OEM Dist, but I dont
want to install until I see if its the Igniter, because I want to be able to return (at a loss).

Talked to a local Toyota repair shop on the phone, he said he could find problem in a hour
or less. He said these small trucks are simple. Right.

I guess if the igniter or the Dist dosent work, then We will find out just how good he is.
Toyota could not find problem after 1 1/2 hours of looking, were doomed.
Thanks for the input.

 

Check two things that might be
Coils do not always throw a code and if they are failing could be the problem.

Knock sensor's also and dont always throw a code or carbon tracks

Check coils 1st
Both of these items when put under load can fail the engine and at idle they run fine

 

I actually replaced the Coil. And I have checked the Knock Sensor, I just unplugged it, and the truck had the same
misses as before, could not tell the difference. But I did get a knock sensor code when it was unplugged.
I know when I finally figure it out it will be something simple, When its running right, which is 75 % of the time
it runs really good. It dosent back fire, it just acts like its missing fire to the plugs for like 1/2 sec, maybe
once, maybe 4 or 5 times in a row, drives me crazy. With all that I have troubleshot, It is still the
same as when I started, 3 weeks ago.

 

How many miles on the plug cables? The OEM have a date stamped on the wires
so you know how old they are

 

Oh about 7 days, after removing old ones, I ohms them out went from 5,000 to 7,000
they are no good at 25,000. I guess they were pretty good, the old plugs had been in there for
around 30,000. They were all a light tan, and in really good shape, but now replaced
with NGK, which is what I pulled out. Its some electrical component thats going out
slowly. Checked the Signal Generator inside the Dist. Its within specs, check air gap
on, inside the Dist on the rotor tooth , its perfect at 0.14in. Cant get specs on the condenser
so thats suspect. When Im driving along, and it starts to happen, if I give it basically full
throttle it goes away. And its getting worse real slowly. Somewhere on here is a thread with everything I had
done at the time, a few things have been added, but are not on the list. Search Phoneman1 should
come up. Thanks for the Input

 

Keep us informed,,,,,,,,,,,,, radiator cap maybe?
J/K but it's almost to that point. Wow, you've got some patience.

 

Well the cables can get carbon tracks and sometimes it’s very very hard to see the tracks

 

Yea its almost a perfect setup for a bad plug wire, but they are new.so
When my New to me Igniter gets here (30.00) , must be coming from the other side of the
Country. I will pop that on there and see if any change. If I only had a Scope, I could
throw it on the coil, go for a ride and see if there is a break down. But I dont, so thats
that. I noticed in the FSM there is a list of OBD2 codes, you get with reg reader, 14 codes
and if you have a Toyota Hand Held Reader you get a extra 22 codes. Wonder if a better
OBD2 reader would get these codes. I cant seem to get a answer to that question.