2004 Taco Hard Start and Low Idle When Cold - PROBLEM SOLVED

On the first start in the morning it requires excessive cranking to start and then will drop below 400 rpms and barely run. The truck runs fine once it's warmed up. Shortly before this problem arose the check engine light came on. Auto Parts store did a scan and got Code 0136. To my understanding that's bank 1 O2 sensor 2 (after the catalytic converter). Since this started, I've cleaned the MAS sensor, run a can of Seafoam through the air intake, replaced the plugs/wires and the fuel filter. As far as I can tell this throttle body doesn’t have an IAC valve (see pics below). I don’t want to keep throwing money into parts on my guesses. Any ideas about the problem? My apologies for the dirty engine compartment. I bought this truck last year from a farm boy who apparently enjoyef burying it above the frame while hunting.

Throttle body facing front


Close up facing front


Facing firewall



Thanks in advance for any guidance.

 

Forgot to say the engine is a 3.4

 

No love for my problem?

 

I've had oddities for years, kind of just lived with it, no codes so

just this morning, started out, get a few miles down the road at the first stoplight, it hovers around 350 rpm. put it in neutral and hold the pedal to get to ~700. by the time I get a few more miles all is good, idle normal sitting in traffic

my assumption is it is another sensor but not bad enough to tell the ECM that there is catastrophic issues

I've done normal maintenance and checked coils but all within specs. tested pressure a couple of years ago and was good still

If I'm bored one day I'll start disconnecting plugs and spray them down with electrical contact cleaner and add a tiny dot of dielectric grease

 

Thanks for the response. The low idle doesn't really bother me, but it seemed to come on at the same time as the hard starting, which is really bad.

 

yeah, the other day I had it crank for 6-7 times. stopped, cranked again for 3 times and it started

I've had a random misfire code a month ago, no longer shows up now, it would do it while it was idling low. I swapped all for necessary testing but same code for Cyl 5. meh

 

Ugh

 

I would check your coolant temp sensor.

That tells the ECM when you have a cold engine to open the IAC for more air.

 

Where is the coolant sensor? Can it be seen in the pics I posted? How do you test it?

 

You could try cleaning the throttle body by hand, running Seafoam through it won't help much if the throttle body has a bunch of gunk built up on it over the years. Taking it off and cleaning it with TB cleaner and an old toothbrush will clean it up nicely.

 

no real IAC on 03-04, electronic :/

 

I did that years ago and wiped it out completely two years ago when i swapped injectors :/

 

Were your symptoms the same as mine?.....hard start and idling too low when cold?

 

That is the year with the strange Throttle body.

Unless one is in front of me i forget.

 

randomly, yes. it's not every time though. sometimes I'll even get a high idle (~1200) even when warmed up. I've though about the coolant temp sensor, but I think it's buried somewhere

 

Mine is consistent and never varies. Also runs like a champ when warm.

 

do this and clean it as mentioned above. Youll see theres a plate on top of the TB with screws. Remove those and clean the little ports. Once you put everything back together they truck might idle rough but it should reset itself. Good luck

 

Okay.

 

I have a question though. As far as I can tell, my throttle body is a transition from 1st Gen to 2nd Gen and has no IAC valve. There must be a sensor somewhere that looks at temperature(?) and adjusts the air to fuel mixture for starting/cold idle? What/where is it?

 

I cleaned the throttle body. No change to the cold engine starting issue.