Baro Sensor Circuit, and IAC issues

InsigniaDelta · 10-10-2005, 09:16 PM

Firstly, I wasn't sure to post this under S-10 or Blazer, but I'm thinking Blazer. Secondly, I'm not familiar with Chevys this is the first one I've done extensive work with... Anyway, here's the backstory.

A lady that my mom works with had a vehicle that wouldn't start, and so asked if I could take a look at it.
*1994 Chevrolet S-10 Blazer Tahoe LT 4.3L V6 CMFI*
It would turn over once, and then it was like something was stopping it. I figured that it could've been the timing chain. After tearing the engine down far enough to get to the chain I found out that the timing chain wasn't the issue whatsoever. As I opened the case, I found a piece of the main bearing laying in it, soaked in smelly oil, the bearing had spun.

Fast forwarding through all the crap, she ended up saying that she wanted a new engine put in it, $2100 later, I had a remanufactured engine in.

Here's where the question comes in.

The IAC valve was unhooked, the connector on the wiring harness didn't fit it, for some odd reason. I took note of it, and hooked everything on the new engine up, with the exception of the IAC valve and connector. The engine turned over after it was all in, but it wouldn't start. Spraying gasoline into it directly got it to start, and it sounded ok, I gave it some gas, and it sounded great. After a few seconds of idling, it started to sound like it was missing, I tried to adjust the timing and then it died. Yeah, I know, self-adjusting timing. I looked, and the check engine light was on, and I got two codes, one about the coolant temperature sensor which I broke dropping the engine in, no biggie. The other one I get, is about the Baro Sensor Circuit. Which I assume is Barometric pressure. I'm wondering, pretty much, if the fact that the IAC valve is unhooked is making the idle really rough, and could be bringing up the Baro Sensor Circuit code...

Also, the exhaust pipe going into and out of the cat is abnormally hot, it almost glows dimly orange. I'm assuming that maybe the air/fuel mixture is too rich, causing the rough idle, the overly hot exhaust, etc. And if that could've led to the spinning of bearings in the latest engine she had put in, which only lasted 10k miles, and she said it never ran right or smoothly with that engine in.

Sorry that was so lengthly, didn't want to leave anything out that would've been important.
So...
1994 Chevy S-10 Blazer Tahoe LT
4.3L V-6 CMFI (Not CSMFI)
IAC Valve doesn't plug in
Baro Sensor Circuit Error Code
Rough Idle
Hot Exhaust

Thanks in advance for any and all help.

DINO55 · 10-10-2005, 09:48 PM

The Glowing exhaust pipe B-4 and after the cat is a sign of a restricted cat converter, also get a new connector on the wiring harness for the IAC and hook it up properly for starters.

InsigniaDelta · 10-13-2005, 06:39 AM

Alright...

I had the connectors hooked up wrong, I had one of the 4 prong connecters plugged into a 5 prong plug, and so I had a 5 prong connector, that wouldn't fit the IAC valve. Got that squared away, and the code disappeared.

Unhooked the cat, and it started right up. Gutted it, works fine now, just an issue of loudness, gonna have to see if she wants to pay to get it replaced, or run it gutted. Replaced the Coolant Sensors, and all is good now, no codes show up.

Thanks DINO55 for your help, cuz yeah, it was apparently a clogged cat...

P.S. The Cat LOOKED good though, I could see through all of it, but we gutted it anyway, and it worked so yeah..

DINO55 · 10-13-2005, 11:37 PM

Glad to help and everything worked out for you

BlazerLT · 10-15-2005, 01:07 AM

Quote:

Originally Posted by InsigniaDelta

Alright...

I had the connectors hooked up wrong, I had one of the 4 prong connecters plugged into a 5 prong plug, and so I had a 5 prong connector, that wouldn't fit the IAC valve. Got that squared away, and the code disappeared.

Unhooked the cat, and it started right up. Gutted it, works fine now, just an issue of loudness, gonna have to see if she wants to pay to get it replaced, or run it gutted. Replaced the Coolant Sensors, and all is good now, no codes show up.

Thanks DINO55 for your help, cuz yeah, it was apparently a clogged cat...

P.S. The Cat LOOKED good though, I could see through all of it, but we gutted it anyway, and it worked so yeah..

Your cat was probably shot due to your CPI injector leaking fuel into it.

You best be checking your CPI injector for leaking before it ruins your engine.

Search for CPI injector.

InsigniaDelta · 10-15-2005, 08:51 PM

How do I know if it's bad?
Everything is running fine, but we didn't have the distributor tightened down, and the next day we went to start it, it took some tweaking to get it running. We bent a fuel a little bit dropping it in, so I was wondering if that possibly is leaking so slightly that it doesn't hold pressure after it's been off for a while.

So since we're already into this lady's Blazer so deep, we're going to replace the fuel lines going into the intake manifold, and the ones inside. While we're at it, we can check the CPI injectors I guess, I just need to know how to go about that.

Thanks again in advance

InsigniaDelta · 10-15-2005, 08:54 PM

Minor Correction since it won't let me Edit...

The distributor had turned a little so I couldn't tell if it was a fuel line issue, or the distibutor, but it's timed perfectly and tightened now, so I hope it starts right up tomorrow. I'm taking it for a week, to make sure there are no other issues. If it doesn't, now I'm wondering if it's just the fuel lines, or that injector like you had mentioned...

BlazerLT · 10-15-2005, 09:13 PM

Doa search for CPI injector, you will find lots of information already displayed.

InsigniaDelta · 10-16-2005, 05:08 PM

For the most part, I can only manage to find CPI Injectors for sale, roughly $300, and the regulator for like $40... Can't seem to find too much on checking if it's faulty or whatnot...

Will keep looking

BlazerLT · 10-16-2005, 06:05 PM

http://www.automotiveforums.com/vbul...archid=1214785

blazee · 10-16-2005, 07:29 PM

Quote:

Originally Posted by InsigniaDelta

For the most part, I can only manage to find CPI Injectors for sale, roughly $300, and the regulator for like $40... Can't seem to find too much on checking if it's faulty or whatnot...

Will keep looking

Here's the info that you're looking for:
http://www.automotiveforums.com/vbul...d.php?t=462726

InsigniaDelta · 10-17-2005, 09:40 PM

Thanks for the links

LT, your link came up with no resutls, I did a forum search and couldn't find anything either...

blazee, your link came up with some useful information, guess it's going to be mostly common sense...

I'm getting sick of taking the intake manifold apart... Haha, but I have a minute vacuum line leak near there anyway that I need to investigate. I'll pull of the plenum and see what I can see. It wouldn't suprise me to find that it's leaking, after reading that the regulator can kinda leak and hold pressure intermittently.

As far as starting up... Sometimes it'll start after like 1.5 - 2.5 seconds of cranking. And other times, it won't start first try at all, but like 1 - 2 seconds on the second try... I'm wondering if that isn't the regulator randomly leaking...

The vehicle sat for like a year and a half... I'm gonna finish the gas that's in it, put some dry gas in it, fill it with medium or high octane, and see if it was just maybe fuel issues. I replaced the filter, but I'll do it again after I run the dry-gas through it and such. Gonna put some injector cleaner in there too.

Let me know if you guys have any other tips to get things going well, I don't want to let this lady down, afterall, she's shelled out over $3000 already. $2100 for the engine itself, roughly $300-$400 for parts - coolant sensors, front pads and rotors, cap and rotor, spark plugs, and $700 labor. So if there's anything I can do to ensure that things run smoothly for her, that'll be appreciated.

The only issues I have that I know of, is the hard starting occasionally, a small exhaust leak in the joint btwn the y-pipe coming from the manifolds, and the pipe going into the cat, since it was sealed and rusted, and I had to really yank to remove the cat to gut it, a small, tiny vacuum hose leak near the intake manifold, and a very, very slight "ticking" "tapping" something, that I can only hear in the cab, and at idle... Not sure if it's the exhaust leak that I'm hearing underneath me or no.

Well, thanks in advance, once again

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