Bad acceleration

[yotadude]

Ok so ive searched this and found many ralated threads but none seem to match the symptoms that im experiencing. Ive got a 94 FJ80 and. 153k miles.

Symptoms:

Immediatley after startup, when engine hasnt run in about 3 hours or more. When in park or neutral it runs fine. When in R or D the idle lowers but still runs fine with the occasional slight lull. When accelerating it feels like the distributor has water in it like i just drove through a deep water hole or something. But there is no water. I does this when accelerating from stop or just accelerating. Does not happen when revving the engine in N or P. The wierd thing is, after the engine warms up or after the first 5 times or so of accelerating, it gets like 80% better and now just becomes sluggish. Also during the bad acceleration, if i accelerate hard or even come close to punching it, I hear a pop but have no idea where its coming from.



I have recently changed the plugs and plug wires.
I'm completely puzzled. Thanks in advance. Let the flaming begin.

 

[xoemor]

Im having the same problem here on a 1994 1FZ-FE. Hope someone can help Us.

 

[ShawnTRD]

Do you know/remember when the fuel filter was changed?

 

[SUMMIT CRUISERS]

As Shawn said, change your fuel filter then change the fuel pump sock (pre-strainer) and lastly the fuel pump.
My 92 was stuttering (and backfiring/popping) after about an hour of driving, changed all the above including the FPR and relocated the EFI relay inside the cab (specific 91-92 problem). The sock and pump fixed it.

 

[Layonnn]

I have recently changed the plugs and plug wires.
I'm completely puzzled. Thanks in advance. Let the flaming begin.

Plugs all gapped properly?
Make sure all spark plug wires are firmly connected as well.

That would be the first two i would check if this just started happening right after plug and wire change.

 

[xoemor]

Its a very extrange problem cause when i push the acceleration pedal all The way down the symptoms desapear. And again the symptoms present just for a minute Or two before the engine get warm. Its no MAF problem?

 

[timer00]

I have the same type of issue.. lulls a bit before taking off until full warmup and then runs fine. I will put off commenting on fixes because I have not done a tuneup/fuel filter change yet.

I did f up my "MAF" sensor where you break off the 3 metal tabs from their solder points and had it resoldered and worked again so I don't know if that has anything to do with it.

Before the "MAF" screwup it didn't lull on cold acceleration so who knows but I don't have popping or anything plus the fact it goes away after 5 minutes doesn't bother me much.

 

[yotadude]

Do you know/remember when the fuel filter was changed?

Have not changed the fuel filter. Could you tell me where its at?

Plugs all gapped properly?
Make sure all spark plug wires are firmly connected as well.

Got the plugs from pre gapped from CDan. They all had the same gap from what I remember. Ill go check to see if the plug wires are firmly connected.

 

[vbcrush]

I have this issue also. Sluggish from a stop until engine warms up. Runs fine at WOT.

 

[ShawnTRD]

Have not changed the fuel filter. Could you tell me where its at?

I can and you won't be happy. It's under the intake plenum.

https://forum.ih8mud.com/80-series-tech/41898-how-do-you-change-fuel-filter.html#post460157

 

[xoemor]

My filter and cables are just a month old. when i replace it nothing change!!!!

 

[yotadude]

Checked the plug wires. Theyre all good. Still runs the same. Ill change the fuel filter when I get home July 22. Thats where the filter is. Tried adjusting the Throttle Kick Down Cable. Even though it wasnt where it needed to be per FSM it didnt help any to adjust.

 

[yotadude]

I read some threads about the IAC valve causing the same problem but I cant figure out where its at. Do yall think that could cause the problem. Also, is it hard to remove and clean the throttle body. Is there anything that i should keep in mind when taking it apart and putting it back together.

 

[arndog123]

IAC valve is on the throttlebody next to the TPS.

 

[yotadude]

IAC valve is on the throttlebody next to the TPS.

Thanks. Ill check it out.

 

[yotadude]

Tried adjusting the kick down cable with no changes. Tried adjusting the throttle cable but that just makes it idle higher. I have found that if I start it up and let it run for a while it doesn't feel like it wants to quit when I press the gas but still acts really sluggish and the acceleration isn't great. I still want to fix the problem though. I'm starting to feel like I'll never fix this thing up. I know it's only a six cyl but there is no way this is what it's supposed to run like.

 

[GunFuFighter]

FJ80 sluggish after ECM replacement

You know Im new to the forum and was told by a few of your AZ members to check on here for a fix to my problem.

I have a 93 that was having Limp mode problems with the "3 code" bad ECU thing going on I have read about. I found a new ECU and have since replaced it. Now the only ECM code I get now is "5" "02 sensor". what it does now.

when I start it up it runs fine when I rev it and such, and when its cold it runs strong and good power. Once the engine warms up the engine light comes on and it has NO power. its very sluggish. I can not figure it out.

is my ECU that I got bad still?

ANy help would be great.

 

[CruiseOrlando]

I must have missed this post earlier.

It's your O2 sensor.

I had the same problem - but mine was brought to light after a run thru the swap. I got water in my O2 sensor connector... tell-tale is that "when I floor it, it goes like it's supposed to"...

Get under your truck on the PS and find your 2 O2 sensors. Take the connectors apart and examine them. Put dielectric grease in there.

You might find cut wires, or you might just find the sensors themselves are bad - there is a testing method per FSM - I don't have it handy at the moment...

 

[Alleycats]

I also had a stuttering issue on take off and replacing the 'fuel pump sock' fixed it. While I had the fuel pump out I cleaned the connector out which was corroded and put a little dielectric grease in there for good measure, since then I've had no problems. Maybe you could also measure that your TPS is is spec?

 

[GunFuFighter]

Ok so I had my buddy plug his 6k$ machine up to it and it was code 55 not 5. Knock sensor was knocked completely off during head gasket replacement. Runs 100% better thanks to Kevin from desert tool service sold me a used one. Still doesn't accelerate great but ill try some more stuff for that. No more engine light!!! Thanks