'88 S10 Blazer Timing Issue?

Thanks,

It wasn't something I had thought of -- perhaps I didn't get it all the way down. I'll give that a try -- thanks.

-Joe

retard/advance

I'm going to give the intake manifold a shot. I didn't torque them correctly (brain fart) or in the correct order. If I loosen them, and re-torque in the correct order, might this work? Or am I better to remove, reapply some RTV, new gaskets, and do it correctly?

Thanks, Joe

thedistributor

How about the heads? Did you torque them in the correct sequence and to the correct specs? If not, she'll be eating antifreeze again in no time.

Doc

retard/advance

I did correctly torque the head, but when it came time for the intake, I didn't know which bolts went where and was scrambling.

Last night I loosned all the bolts on the intake, and retorqued in the correct sequence. That seems to have solved the ECM error 33 (MAP) and the sucking sound.

However, it still hesitates, has no power under load, and won't idle.

No codes are ever set.

My markings on my timing plate are a bit rusted, so I'm not sure what the correct mark is. From right to left the timing plate looks like this: |_________/\___| \/ \/ \/

(I don't know if that came out -- or looks right)

I checked on a '88 Silverado and I think the 0°BTDC is the indented mark, is this the same on the '88 Blazer?

When timed to that mark, it didn't idle very high. I couldn't see the RPMs since I was in the engine compartment. It would stall as soon as it approached let's say 1200.

When timed to the first protruding mark, it idled a bit higher, but still stalled.

I didn't try any other marks, but as I went to the third protruding mark (12°) it did idle higher, but I didn't even try that one.

I know I have the correct mark on the damper pulley, and I disconnected the brown wire.

I decided that I needed to do something, so I was going to tighten my TBI. I checked the book and it said 144-inch pounds, but I was tired and read it as

144 foot pounds! This seemed wrong, and I looked twice more... and I said "well... maybe it needs to be thight!" So I set the torque wrench to 100 pounds and went nice and easy. It didn't get hard to turn, but I did break a bolt. After much cursing and telling myself how dumb I was (once I realized it was inch pounds) I pulled the TBI off and the broken bolt came right out.

Once I had the TBI off I realized my Air Idle Control Valve (6 months old) was not tight, although it was 1-1/8". The Throttle Position Sensor (12 months old?) was tight, and I checked with a voltimeter and it looked like "THROTTLE CLOSED" gave about 8 ohms of resistance, and "FULL OPEN" gave 1.5. I compared that to an old one I had lying around -- my new one had a better range where as the old one only went as high as 6.

My plan at the moment is to get a new TBI gasket, a new TBI mounting bolt and try that. I want to avoid buying more sensors ;)

Am I on the right track? or is there something else I'm missing?

Thanks, Joe Webster 'Truckless in RI'

You said you pulled the push rods out? Maybe you got 1 or two too tight keeping the valve(s) open. Is it just low on power and stalls or is it a "miss"? If it is a miss it could be the valves or maybe just 2 plug wires switched. I would put a fuel filter on it too if you havent allready. The bigger or different mark is going to be 0° .

Scott might be onto something. What procedure did u use to retorque the rocker arm bolts?

Doc

Then do that first; it's a cheap rule-out.

Doc

disconnected

cleaner(maybe

Reluctor? What/Where is that? I don't have my book handy, but I'll look when I grab it

Thanks, Joe

Hi Everyone,

I've retorqued my intake, that stopped my error code 33 (MAP sensor) and the sucking sound. But it still had problems idleing and hesitation/no power under load. Actually even in neutral -- after about 1-2 mins -- it does the same thing.

So I replaced my TBI gasket and checked the TPS and IAC valve. Once again, I timed it. Still has problems. Actually, now I'm getting code 33 again -- and all I did was the new TBI,TPB,IAC -- and I'm sure they are tight enough. I don't hear a vacuum leak.

Something I did notice. When the engine is first starting up... it will hesitate a slight bit, the engine/computer recovers and sets a code 33. While the SES light is one, the engine runs great, not hesitation, and has power under load. Once that SES light turns off... it all goes south. Am I correct in assuming that this is when the emission system kicks in? If so, does that give anyone a clue to as what's wrong?

This one is driving me nuts... well -- actually I'm doing alot of walking and no driving!

Thanks for the help guys, Joe

thedistributor

Forgot to add that I tried to replace my fuel filter... but the connections were rusted a bit and didn't want to come loose. I sprayed with wd-40, we'll see how they do tomorrow.

-Joe

retard/advance

Thanks,

I got a tube of RTV in the intake gasket. I didn't use it all, the instructions said just a 1/4" i think. I figured too much would be bad... ;) I'll try that tomorrow.. PITA -- but what you said does make sense.

Thanks for the info, I'll let you know how I make out.

-Joe

Joe, did you try driveing it with the electrical plug unplugged from the MAP? This will put it into "limp in" mode and if it is the map it should run ok. If it does run better check very carefully the map vacuum hose. If it has good vacuum then replace the map. The intake torque is not *that* critical. You probably have it sealed well. GL

>

That tall bead of silicon on the ends of the intake prevent oil leaks, not air. You shouldn't be using silicon on the gasket itself. If you did, that's probably where the problem is, since it's just about impossible to get a nice even coat all the way around. I'd not look at the intake anymore for your problem, though. Time to look at wiring or a MAP sensor, or the hose going to it.

I already replaced the MAP sensor =(.

I didn't check the vacuum of the hose. I'll check that and try the "Limp-Mode".

Thanks, Joe

I did put RTV (not silicone) one the intake gasket around the water ports as

the book and directions that came with the gasket told me to.

If there is a leak at the front or back of the intake -- wouldn't that allow

the valley to also leak? Isn't that where the vaccuum is created?

I have replaced the MAP sensor, and checked the two hoses to and from it.

The connector looks good, but I'll give the wires another once-over.

Thanks,

Joe

No, the vacuum is in the intake ports. If the front and back leak it is going to leak oil, not vacuum.

How is it created?

-Joe

the vacuum is created by the piston moving down in the bore. the piston moves down faster than air can get by the throttle blades, creating a vacuum.

-Bret