Engine stumbles, trouble code 15 and 32

[351FUN]

Truck is a 1992 blazer. The engine started stalling the other day, too much fuel. There'd be black smoke when it stalled and it would not restart, but unplugging the injectors would have it fire right up for a couple seconds. I've installed a fuel pressure gauge, adjustable regulator, and replaced the o2 sensor with a heated 3 wire unit, all parts I'd had sitting but this gave me the motivation to install them. Its putting out 13# of pressure right now after a fuel filter change, was at 10# before that.

Currently it won't stall but it comes damn close. It will not start if I just turn the key, but if I bump the gas pedal a hair it fires right up. Idles perfect. I know code 15 is because I disconnected the factory water temp probe to install my own, so question one is does the ecm use that reading for anything? Second question, code 32 is giving me multiple answers. Does anyone know what it means on a 1992 tbi truck?

 

[SAATR]

The ECM uses the CTS for a variety of things, like cold start enrichment and switching between open and closed loop fueling. Reconnect the CTS in the factory location and put your gauge probe somewhere else, like the side of the cylinder head.

 

[PlayingWithTBI]

^^^This. Get the proper 2 wire CTS installed next to the T-Stat housing

Code 32 can be EGR and/or MAP sensor.
you can test your EGR valve with a vacuum pump, see if it holds a vacuum. Also, while idling press the EGR diaphragm and see if your engine starts to sputter. The passages in the intake manifold may be clogged up too.

Indications of a failed MAP sensor include hard starting and running rich. Put a scanner on it and see what your MAP sensor is doing.

 

[351FUN]

^^^This. Get the proper 2 wire CTS installed next to the T-Stat housing

Code 32 can be EGR and/or MAP sensor.
you can test your EGR valve with a vacuum pump, see if it holds a vacuum. Also, while idling press the EGR diaphragm and see if your engine starts to sputter. The passages in the intake manifold may be clogged up too.

Indications of a failed MAP sensor include hard starting and running rich. Put a scanner on it and see what your MAP sensor is doing.

Do we have a MAP sensor? Where is it hidden?

Looking at the truck after I posted that, the EGR is disconnected. The valve to solenoid is hooked up, but the solenoid to I assume engine vacuum is not.

 

[351FUN]

Lmao that was it. Put the old sensor back in, cel went off and it runs like a champ.

 

[PlayingWithTBI]

Lmao that was it. Put the old sensor back in, cel went off and it runs like a champ.

Good to hear you got it

Do we have a MAP sensor? Where is it hidden?

Yepper you have 1, ha ha.

FYI, here's some of what you're looking at -
Yellow = MAP sensor, vacuum line from the back of the Throttle Body goes to it
Orange = EST Module, it's connected to the Knock Sensor
Red = EGR Module, vacuum line goes to it from the front of the TB (you found that )
Blue = TPS
Green = IAC Valve

HTH

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Here's where the lines are

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[351FUN]

I would have never guessed that! I had to replace the iac shortly after getting the truck, and I've seen the tps when I rebuilt the tbi unit, but I had no idea there was a map hidden in there too.

 

[Schurkey]

the EGR is disconnected. The valve to solenoid is hooked up, but the solenoid to I assume engine vacuum is not.

Fix that next.

Which probably means figuring out why someone disconnected it in the first place--failed EGR valve? Failed solenoid? Plugged EGR passages?

 

[351FUN]

Fix that next.

Which probably means figuring out why someone disconnected it in the first place--failed EGR valve? Failed solenoid? Plugged EGR passages?

Honestly I'm just gonna get a new valve and reconnect it, new valves are cheap. Odds are someone removed it because of we didnt have that in my day, all it does is kill your engine kind of stupidity.