'88 Blazer Problems Still

Hey guys,
Still having issues with my Blazer:
1988 Chevy Blazer S-10 4x4 4.3 TBI/EFI Z 203,000 Miles Rebuilt engine at 150,000 Rebuilt 700R4 trans at 197,000
The story (summary from a previous post): The problem I had was a head gasket. So I pulled the intake, both heads (as well as all accessories up front) and replaced the gaskets. #5 cyl had the problem and was full of coolant. I put the heads back on, reinstalled the intake, everything else. Retimed it and had a code 33 (MAP Sensor). I would not idle, and had no power under load, I also heard a vacume leak. From the suggestions on these groups I retoqured the intake (as I didn't do it correctly the first time). That fixed the sound, code 33, and the idle (still a little rough) but still no power. It has power for the first minute or so at startup (while the SES light is on) but once that goes off, it's almost not enough to get it moving. I had replaced the MAP sensor, TBI gakset and EGR valve. I checked all my vacume lines, everything looked ok. Restarted, the code 33 came back, but no sound of a leak and it still idles (rough)
Today I spent 2 hours listening for a leak, checking lines, and just giving everything a good twice-over. It's running extremely rich, after all of this there is a nice black spot on the pavement ;) It seems it only has a black puff after I rev it and it's coming back down... so I assume it's loading up? The O2 sensor is probally shot at this point - but no code 13? Aside from that, when you start it, it has problems getting to idle, but after 3-5 seconds it gets there, and trips SES.
Now I have a code 33 and a 34. The book I have lists a 33, 34 as:
33: 1. Mass air flow (MAF) sensor - signal voltage or freq. is high during engine idle. 2. Manifold absolute pressure (MAP) sensor - signal voltage is high during engine idle. (Note: Engine missfire or unstable idle may cause this code)
34: 1. Mass air flow (MAF) sensor - signal voltage or freq. is high during engine idle. 2. Manifold absolute pressure (MAP) sensor - signal voltage is low during ignition on. 3. Pressure sensor circuit - signal voltage too high or low (carb. engines only)
So, I thought that if I burned out the O2 sensor while trying to get it timed (forgot the tan wire), perhaps that is causing the rich condition, giving me a rough idle and tripping the 33.2. The idle isn't that rough, but it was before (plus many missfires ;)). However, I don't know what would be causing 34 -- aside from a MAF sensor... perhaps I should replace that too?
I guess I'll spend the $$ on a MAF and a O2 and see where that gets me, but I don't want to put in a 02 and cake it up with carbon it that won't help -- I rather replace that after.
At this point I'm almost ready to bring it to a shop -- OMG I HATE THAT. Partly the money, mostly the principal!
Before I do, I wanted to see what you guys thought.
Thanks, you guys have been a big help,
Joe
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Well the book I bought (with the "scan tool reader" from Kmart for 19.99) is useless. The codes wern't really for my truck, the ones I got from troublecodes.net are as follows:
33 MAP sensor signal voltage was too high (low vacuum) for 5 seconds when throttle opening was under 4%. 34 MAP sensor signal voltage was too low (high vacuum) when engine speed was over 1200 RPM, or the throttle angle was above 21% when engine speed was over 1200 RPM.
Those make way more sense. Now that still looks like to me that I have a vacuum leak, but I can't find it.
So I guess my questions are:
1. What's a good way to check for a vacuum leak? A) I remember someone mentioning something about a bike inner tube and pressurizing something? That way you could hear a leak w/o the truck running. B) Somone also suggested to spray gumout/carbcleaner around and see where the engine surges. Anything I should focus on, anything I should avoid?
2. Could a crudded-up, burnt-out o2 sensor cause the engine to run that rich (and therefore bad?) and NOT trip a code 13?
There isn't a MAF sensor on my truck ;) and the 02 sensor is on 19.00 -- now I don't feel so bad about burning one out.
Thanks, Joe
<snip>

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You probably do have a ruined 02 sensor, the coolant through the exhaust system WILL mess it up, you should have your cat conv checked out too, it may be blocked up from the chemical reaction of the coolant through it. You definitely have other problem(s) as well. The 02 sensor by itself won't cause the problems you describe.

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disconnect the exhaust system at the manifolds. Start the truck. does it run better now (granted it WILL be louder) if it does then the cat is clogged up.

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Use a 3 or 4 foot lenth of heater hose to check for vacuum leaks. Stick one end on your ear and listen around with the other. It will amplify and pinpoint all the hissing sounds from a vacuum leak. Works great. If you find a leak you will know for sure, it will be loud. Like Ed said, the O2 wont cause it to run that bad. Best fix the rest first. Did you check for good vacuum to the MAP?

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I've seen this several times when the rockers are overtightened. If you have more than 4 threads showing on any of the rocker studs, I'd put money on it. Did you run a compression test on it?
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I used the proceedure in my books to tighten the rockers. The process was pretty much turn to TDC, tighten (specific list) 50% of them. Then turn it 180 and to the remaining.
When it runs, no tapping can be heard from the heads. My uncle (old school) grabbed a stick and put it on the covers and said it sounded good. So I'm confident I had that right.
No, I have not run a compression test, I will and post back.
This Tuesday I dropped my truck off at a local shop (3 times detached from the owner -- so I figured better him than somone I don't know at all). Called me a few minutes ago telling me that he checked all the vaccume lines, all looked ok. Then he pulled the valve covers and re-adjusted the rockers. He said he couldn't find anything wrong either. $100 *sigh*, well I know my work is at least worth $100 I guess ;) I'll pick it up Monday and coax it home. He did have a few questions for me.
1) Question: Did it run like this before you did the head gaskets? Answer: Yes, but I assumed that was because #5 cyl. was FULL of coolant.
2) Question: Did you have a valve job done? Answer: No, it was done ~50,000 miles ago, I didn't see a reason to.
3) Question: Did you get the right intake gasket? There are several out there, perhaps you have the wrong one? Do you have the old ones? Answer: No, I don't have the old ones. I just got them at AutoZone.
Now I checked on the internet, and I really can only find ONE gasket on the sites I looked at. All were Felpro MS93346: http://www.pickproparts.com/pictures/single.aspx?linecode l&partnum=MS9334 6
I had restrictor plates on the old gaskets, and the new ones were blocked all togeather -- that's fine I understand. Otherwise they were a perfect fit -- seemed to me anyway.
Could there be a connection between my Code 33+34 and a clogged exhaust system? Could that stop the vaccume?
I want to solve the code 33+34/Vaccume leak before I start looking at other things... does that make sense?
Thanks! Joe
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Paid for the work today, will drive it home later tonight (maybe).
I talked to him, he said he found a clogged vacuum line. Since he knows me he looked at me and said "before you replace sensors, check the line for vacuum first" -- and he's right -- I suppose ;)
So the code 33/34 are gone! So perhaps at first, it was that I had a leak. Then I fixed the leak, but then the new improved vacuum sucked some $hit in to the line.. thus giving me the code back.
Now that the 33/34 is gone, I'm going to replace the 02 and see where that gets me.
Fingers crossed, Joe

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