99 2.7 won’t idle or run without backfire and dying

So I’ve posted about this truck before. The cat clogged on it so I cut it off drive it home and that was a year and a shit ton of money ago and it still won’t run. No code no engine light on. I’ve replaced every sensor , every vacuum line, plugs , wires exhaust (no cat) and dropped the tank twice and cleaned out the entire fuel system and intake sludge. Same shit it is hard to crank and backfires spurs sputters and dies when you touch the gas. I replaced the injectors again yesterday and thought I was good but nope same crap and fouled all the plugs again. Any suggestions the obd2 scanner is out because it shows everything good.

 

check the fuel pressure, might need a pump

 

Just what had caused the cat to clog?? How was the issue fixed?

Was it an oversight you did not mention changing the fuel filter or fuel pump ?


Checking the fuel pressure or doing a compression or leak down test?

Your OBD device is connecting like it should ?

 

I’m on pump number four and filter number 5 or 6. I have a case of filters and two spare pumps on hand. Tank has been cleaned out twice dumping thirty gallons of gas out and every sensor front to back has been replaced at least once .this is 6 or 7th set of plugs it’s fouled out. Like I said no engine light no codes according to diagnostic tools it’s running like a champ. Not! I’ve spent a shitton of money on it thus far and should have gone with my first thought and shitcanned the 2.7 chopped my frame and put a C4 Cummins in it. It would have been cheaper lol any ideas out there I would appreciate some input I’m at a loss and been looking at it too long

 

Not sure what clogged the cat possibly bad fuel and almost 400,000 miles on it . It clogged up quick fast and in a hurry with no warning I had to cut it off in the middle of a county road with a sawsall . Tried multiple scan tools obd2 readers , had two mechanics out to look at it and still at square one

 

Also did a compression test they were within 110-115psi range on the unit gauge I was using. Fuel rail pulled and cleaned ,new injectors , new fuel pressure regulator . It’s all new I’m at a total loss

 

This has been going on for a year and $6,000 later I’m still at square one. I cut the cat off drive home and it never moved again

 

Sounds like its out of timing....


which could be ecm.......is this a manual or auto?


auto ecm's are a dime a dozen.......manuals are not.

 

Is the egr valve functioning correctly?

 

Update pulled valve cover and valves are all good timing chain good, oil pump is apparently working good the bolts all had puddles in the tops . Timing chain was tight with no wear and timing is spot on. Now what lol . Firing order is 1342 ? Moving front to back one being the front position ? Oh and zero metal shavings in the motor .

 

It’s a five speed manual

 

I’m about to the point of putting a c4 tdi in it like my RR Defender has those things are bullet proof just can’t park in the driveway lol

 

I would verify that the timing mark on the harmonic balancer hasnt slipped. Take the plugs out and insert a long wooden dowel into cyl #1 and turn her over by hand and see if TDC according to the dowel is TDC on the balancer.

 

The Big 3
Fuel/Compression/Spark (timing)

-Sounds like u got fuel covered bc of prior work/parts RR’d
-Assuming engine ran B4 cat got clogged, that confirms compression
-spark/timing unclear

rich timing could (in theory) make cat clog faster than expected
Especially if over a long period of time

just guessing here
But I would put a timing light on that thing to rule out ‘no idle/back fire’ condition

 

Popped the valve cover of pulled number 1sp and hand rolled the timing chain to tdc#1 and then rolled the cranks over several times and valves are working all cylinders are burping air from compression not a speck of metal shavings in the motor . Cams turning properly . Timing is on point i had a Toyota mechanic out to my place to verify just to make sure I wasn’t missing anything and he was stumped . And yes it was running better than a new one before the cat shit the bed. I deleted the cat with the new exhaust those sensors aren’t even making the engine light come on now even thought there is no cat should they be setting off the engine light? Is 1342 the only firing order for the 2.7?

 

I’m at a total loss I’ve been front to back top to bottom and back again and replaced everything and still on square one. I started gathering frame materials today to start building a new frame to accommodate a c4 Cummings diesel and drive train. If I going to keep going at least I’ll be headed in a progress direction. I’m a year in countless emails , phone calls and chats and no telling how many man hours and nada . I’m going to change plugs and swap wires one more time (set 4-5-6 shit I can’t keep track ) and I’m seriously thinking hard on pulling the plug . I love my truck but if it was a horse i would have shit it a long time ago

 

I tried loading a short video with sound so you guys could hear it but it’s not allowed . Anyway it immediately starts backfiring and running terrible as soon as you hit the gas . Plugs fouled again

 

Hmmmm

maybe the OBD port that is not throwing codes is a clue
On many OBD2 codes…..list of causes….the bottom reason is ECM
2 examples:
(These are not your codes…..just examples)

 

Very rare IMO
But could be ECM???

 

Next step I guess . The yoda mechanic that I had out has a 79 yoda daily driver first and last new vehicle he’s ever owned . He also has an 84 model . Both purchased new one owner vehicles all original so he knows Toyotas inside and out and he was stumped . He said he’s got a new ecm we’re going to try out and see. Just doesn’t make sense it ran fine and the cat clogged and ruined all this shit in a 40 mile drive home all in one day.