Hey,

I've got a 2002 Chevy Blazer, and I've had the P0172, and P0175 codes coming on and off for the last year or so and lately I've been replacing different parts because my truck's performance had been going down.

So far I've replaced th O2 sensors, the ABS sensors, the fuel pump, the fuel filter, the distributor cap and rotor, the spark plugs and wires, the ignition coil, and the spider injector.

I also checked the lines from the injectors to the vapor canister and fuel tank, and they're all clear so as far as I can tell by the replaced parts and inspection there is nothing or shouldnt be anything wrong with the fuel system now.

With the replaced ignition coil, plugs, wires, cap, and rotor I don't think there's any kind of electrical problem but I can't rule it out completely.

Anyways more to the point I had it diagnosed again today and they told me that my lower intake manifold is leaking coolant. I was wondering if anybody knew for sure whether this could be the root cause of my truck running in a rich condition?

It makes a little sense to me because as much as I can remember I've been getting the P0172 and P0175 codes as long as my coolant has been low and I've had to refill it occasionally, which out of my own ignorance I thought was normal. Haha, I thought coolant just emptied out little by little, but my father told me today that it shouldn't.

So I was thinking if my intake manifold is leaking coolant it could be causing the rich condition since I've read cooling system issues can cause the rich condition but what I read didn't specifically say anything about coolant leaks and only spoke of thermostat or sensor issues so I'd like some confirmation from someone please.

Thank you,
Matt, IL

 

The LIM gaskets leaking coolant OR vacuum will not make the engine run rich, guaranteed.

You've replaced a lot of parts... were they all diagnosed as being bad?
Are there any other DTC's in memory?
Have you checked fuel pressure and leakdown?
Have you checked camshaft retard?
Are you using AC Delco #41-993 plugs?
Are you using AC Delco cap & rotor?
Are the IAT & ECT sensors both indicating ambient temperature with a cold engine?
Have you checked long and short term fuel trims?
How many miles are on the oxygen sensors?

Most of these things can cause a rich condition and may or may not set a DTC in memory.

 

Yes, the parts I replaced were diagnosed bad.
There are no other DTC's.
The fuel pressure is also fine, checked that when checking the lines for clogs.
"Have you checked camshaft retard?" Really? That's not nice and I'm no mechanic so I'm doing the best I can with what I've read and what more experienced people have told me, partly why I posted this question in the first place. I also apologize for adding to my apparent ignorance but what would the camshaft have to do with it if you'd be so kind to tell me??
Yes, the cap, rotor, and plugs are all AC Delco.
I havent checked the IAT & ECT sensors.
I did check the Short and Long Term Fuel Trim and while I can't remember the exact numbers, they did indicate a rich condition.
I'm unsure how many miles are on the O2 sensors.

 

First time I have for real LOL'd. Camshaft retard is an actual term for what an engines status is with regards to retard or advance, unless your the funny guy. He ment no disrespect.

 

Never thought about it being interpreted quite like that.... and spittybays is correct. It's an adjustment that is done by turning the distributor to precisely align the camshaft position sensor to the actual camshaft position. It is measured in degrees of advance or retard. It needs to be checked, and adjusted if necessary, from time to time and any time the distributor is removed. If it's off, it will cause driveability issues. If it's off more than ~27 degrees, it will set DTC P1345.

What is the fuel pressure and does it hold for at least 10 minutes?
You'll need to check IAT & ECT with a scan tool, along with oxygen sensor readings and response times.

 

So how do you know intake manifold leaks won't contribute or cause running rich conditions? I've read an article and been told by a few other people that it can.

 

If by some small miracle, coolant were to find its way to an intake port, there would be clouds, not just little puffs, of white smoke from the exhaust. The engine would misfire, and the exhaust, (from burning the coolant) would contaminate the oxygen sensor causing it to report a lean fuel mixture and set lean DTC's in memory. If an intake gasket leaks vacuum, either internally or externally, that would also cause a lean fuel mixture and lean DTC's would be set in memory.

 

I'm going to replace the intake manifold gaskets, regardless if it fixes the rich condition or not it's still leaking and needs replaced. Where's the best place to order a replacement gasket set? I read elsewhere that the current market antifreeze/coolant Dex Cool is what's ruined the gaskets on my model blazer and similar ones so I dont want to order like the same gaskets that'll eventually get ruined also. Could someone tell me where to order the new and improved gaskets that wont be ruined by dex cool, please?

 

DexCool has absolutely nothing to do with the gasket failure as we have discussed and explained many times. It is the fault of the GM gasket design and construction. Get the Fel-Pro replacement with the metal core and you'll have no more headaches.

 

I agree ^^^

Felpro part number MS98002T. If you clean everything up properly, use thread sealer on the manifold bolts, tighten them in the proper sequence to the proper torque spec, they will not leak. If you flush the cooling system every 3 years or 36K miles, Dexcool works fine. Like anything else, if you neglect it you'll have problems, guaranteed.