I'm running out of options runs rough first five minutes bucks and miss fires

M

moco2448

Member
I bought this truck with a burnt vavle on number one I replaced the head with a reman ran fine for a month and then began my struggle so the problem is a semi rough idle when dead cold and miss fires bucks and overall runs like **** under 1/4 -3/4 throttle runs fine under full throttle and sometimes even when fully warm the idle will dip down low to 600 esh at a stop then perk back up if you blip the throttle even when warm from a dead idle you can hear and feel a hick up.
It idles fine and starts fine when hot starting but still runs like **** under load 1/4-3/4 throttle

1998 trd 2.7l five speed
So far replaced
New head
Injectors
Coils
Plugs
Cam position sensor
Maf
Both temp sensor ( the plug was destroyed and hooked up backwards for a bit. Idk if that ****s em up)
Throttle position sensor
Water pump
Thermostat
Fuel filter

The truck has no codes
Mechanical inclined please help Ive run out of ideas all done in the last five months
 
[emoji115] Yup, sounds like you've got a vacuum leak, and it sounds like a pretty good one. You may not be able to hear it but I'd be willing to bet that there's a 1/4 or 3/8 line left open somewhere. I've done it before, prob most of us have. Crawl all over it, use mirrors and lights if need be.
 
I've tried spraying carb clean all over the place to see if it changes but I'll look into that thanks it wouldn't be the first time
 
This isn't my first 2.7l I know the vacum system fairly well I did a turbo on my last all from scratch no kits all custom by me myself and I . And there isn't a leak I've spent the last hour out there checking and rechecking I've had other noses under there as well and we haven't a leak
 
moco2448 said:
This isn't my first 2.7l I know the vacum system fairly well I did a turbo on my last all from scratch no kits all custom by me myself and I . And there isn't a leak I've spent the last hour out there checking and rechecking I've had other noses under there as well and we haven't a leak
Click to expand...
Add it to the list of things you’ve done. What’s left that could cause your issue?
 
Good point.
The only thing I can think of is maybe that computer temp sensor on the back of the block doesn't like being hooked up backwards and got fryed. But when unhooked it throws a code and runs worse like way worse so I really don't think so I've got good fuel pressure that doesn't leak down it doesn't make symptoms of a bad or dirty iac vavle
 
So update I've reset the computer in hopes to idk in hopes of something well today I got a po172 po172pq . System to rich this is puzzling to me for the clean airfitler and new MAF I installed less then a month ago that being said after all these attempted fixes this truck has never ran quite right it's gotten better but never as it should I've chased one problem only to find another
 
moco2448 said:
So update I've reset the computer in hopes to idk in hopes of something well today I got a po172 po172pq . System to rich this is puzzling to me for the clean airfitler and new MAF I installed less then a month ago that being said after all these attempted fixes this truck has never ran quite right it's gotten better but never as it should I've chased one problem only to find another
Click to expand...
Bummer.
 
I agree with the idea of the 300 k rebuild but when I did the new head there was no build up and everything looked as if well taken care of all being bone stock it's a mystery I will get to the bottom of
 
moco2448 said:
This isn't my first 2.7l I know the vacum system fairly well I did a turbo on my last all from scratch no kits all custom by me myself and I . And there isn't a leak I've spent the last hour out there checking and rechecking I've had other noses under there as well and we haven't a leak
Click to expand...
Just because you're cocky doesn't mean you don't make mistakes. Haha

Ok so... if it's not a vacuum hose then..... @OR17TRD asked about timing, you answered, "coil packs and new cam sensor". Great but are you 100% sure that your timing chain is in time/ correct notch? **** happens.

Have you changed the sensor that was hooked up backwards? I wouldn't imagine a temp sensor matters or would cause problems but ya never know. I have read that these temp sensor can cause crazy things to happen.

You verified fuel pressure, check.

EGR/ PCV valve EGR modulator/ solenoid?

I'll keep scratching. Good luck to ya!
 
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