3.0L ignition (1 Viewer)

[ntsqd]

My 88's 3.0L started behaving odd on cold starts. It would randomly miss until it got warm and then it would run fine. I realized that it was due for at least spark-plugs, so I replaced those with the gaps set to the .032" FSM (& plug mfg.) spec. The plugs that came out were consistently .040"

Started the truck and while I can't hear it dropping any cylinders, it does randomly pop in the exhaust. Figured that I'd likely messed up a plug wire or more so I replaced wires, cap, and rotor. Still pops in the exhaust.

The plugs that I put in are NGK BCPR5EY. I recall that sometimes Toyotas can be sensitive to the brand of plugs used, but NGK's have always worked well in my old 22R.

I am tempted to open the gaps up to .040" and see what happens.

Anyone run into this before?

 

[Curt]

Have you taken a look at your cap and rotor, condition of plug wires? Toyota's can be sensative but usually NGK or Denso work well. I will see what we got on our 3.0 they seem to work fine.

 

[Curt]

just checked Denso 3119 or K16R-U gapped to .032.

 

[ntsqd]

It did this with both the new cap, rotor, & wires and the old cap, rotor, and wires.

 

[toyotaboy80]

How many miles on the engine?

 

[ntsqd]

The odo says something like 285k, but I know that it's been apart at least once and maybe more than that.

 

[toyotaboy80]

Wonder how the valves and seats are at that many miles. Its possible that the seat position changes enough when it warms up that the engine runs better. Does it burn oil? Pops in the exhaust at idle/cruising or on decompression? On decompression could be an exhaust leak.

 

[IslandJ]

I have a lil puff at the exhaust but havent figured out whats causing it. Had it prior to the rebuild and after. New caps, rotor and wires.
Maybe the EGR valve or the many vacuum lines? IDK. Interested to hear how it ends up.

 

[ntsqd]

Randomly pops at idle, have not yet driven it. I did have to be a little rough with the vacuum hose cluster next to the canister while changing the pass rear plug. Guess that I'd better have a close look at them.

My experience has been that all Toyota's burn a little oil when used at high revs. This engine is no different in that regard. It clearly popped it head gaskets with rusty coolant in it at some time before it came to me. It runs too strong to have serious internal issues. I'm betting on a problem in one of the exterior systems.

 

[liveoak]

On the 3.0 and 3.4, the fuel injectors, especially #3 and #6 should always be considered when you start getting misfires. These engines are well known for cooking the injectors during hot soak periods(shutting the engine off on hot days, the heat from the manifolds and crossover pipe migrate back to the engine). Sounds to me like one or more could be leaking, causing cold start and probable random misfires. A lot of times it would have a hard time starting again after shutting down for a few minutes on a hot day.
I've yet to see one of these injectors completely stop working, they always seem to die slowly, causing issues that are hard to troubleshoot.

Any of these Hot Soak issues sound familiar?

 

[ntsqd]

It does sometimes behave like it might not have a pressurized fuel rail on hot starts.
Recommended injector vendor?
I have a 5.3L LS swap that needs to get done and this is holding it up.

 

[IslandJ]

Fuel Injector Parts, Rebuild Kits, o-rings, seal kits, - https://theinjectorshop.com/ rebuilt the oem injectors I had on my 22re. They test them and give you read outs of the performance differences after.

 

[toyotaboy80]

I guess by my definition theres burning oil, and using oil.

Using oil is something every engine does. Aka consumes small amounts oil relative to a period of time.

Burning it is visibly noticed out the tail pipe as blue smoke under load or decel and is a strong indicator of internal engine condition.

Is the engine symptomless once hot, or does it just get better than when cold?

 

[ntsqd]

Have not driven it with it idling like that. Prior to replacing the plugs it ran fine most of the time. Occasionally it acted like it was loading up on cold starts. Was random when it did and didn't do that, but when it was cold enough for frost in the mornings seemed to trigger it more than not.

 

[toyotaboy80]

Any chance the firing order got mixed up?

 

[ntsqd]

Possible but I changed them one at a time and it doesn't seem to be dropping any cylinders. Which is the part that perplexes me the most.

 

[Curt]

shot in the dark but hows the distributor. any play in the rotor?

 

[ntsqd]

Not that I noticed while changing the rotor. There was a thin coating of rust colored dust that I cleaned out.

 

[Curt]

timing?

 

[ntsqd]

Have not changed it from when it ran well.