Hello all and thank-you in advance.

I have a 1995 S-10 Blazer 4WD (4.3 L - VIN W) with 203,000 miles.

About 3 months ago: Car always started fine both warm & cold. One day, after driving a couple miles and engine still cold... huge amounts of white smoke coming from the rear and intense smell of raw gasoline. Engine then suffered a hydraulic lockup and was impossible to turn over. Cylinder #4 was full of liquid gasoline. Drained cylinder and hanged CMFI unit. Engine started.

However, since changing the CMFI, it's been somewhat harder to start than normal and gets more difficult to start as the engine temperature goes up. After fully warming up and sitting for a few minutes, it's nearly impossible to restart without waiting until it cools again.

I'm confused as to why it seemed to run fine while the CMFI was going bad... then runs terrible after the CMFI was changed. Yes, new spark plugs gapped & installed and all sensor wires were plugged back in to all sensors. New manifold gasket installed and cover bolts torqued to proper spec.


During the last week or so:

• Check Engine Light (Code 32) only after warmup.
• Rough Idle.
• Intermittent oscillation at engine idle.
• Difficult to start after warming up.
• Delayed response after removing foot from gas pedal.
• Braking while driving at slow speed (while parking) is VERY difficult due to low vacuum assist.

Handheld Diagnostic Tool show ony code 32 and says that EGR is bad. Troubleshooting book shows both EGR and/or MAP as a Code 32. However something to note is this problem is NOW repeatable... EVERY single time I get the engine warmed up, the Indicator Light throws up a code 32. Shut down and after a few minutes, indicator light clears but code 32 returns as soon as engine is back up to full temperature. Also very hard to start when engine is warmer... the colder the engine, the easier to start.

Right now, I'm leaning towards a bad MAP sensor. If EGR was stuck, I'm thinking I'd get the trouble light ALL the time.

So I'm wondering if anyone has any experience with these symptoms or can give me any additional troubleshooting tips.

Thank-you!

 

did you check the line between the Map sensor and the manifold, any cracks or anything?? the vacuum line is cheap and easy to replace.

 

I have not done much of anything yet... been sick all weekend.

On this engine the MAP is bolted right onto the manifold so I'm not really sure if there are any hoses. If so, I'll definitely check those.

 

Yes- I inspected just now... on mine the MAP is just bolted right to the manifold without any hoses or lines. Just the wiring harness connector.

Contrary to various other troubleshooting sources, my engine refuses to start when the MAP wiring connector is unplugged. Maybe another clue?

 

On your truck, code 32 is the EGR valve. 33 would be the MAP sensor.

I would recommend that you remove the EGR valve and give it a good cleaning. The ECU would not try to do anything with the EGR valve until the truck reached closed loop operation and even then, certain conditions need to be met.

 

Although the Haynes manual also lists MAP failure as Code 32, your statement is correct for my Blazer in that Code 32 is only the EGR circuit.

Everything I've been reading about the Code 32 though seems to indicate that it doesn't necessarily mean the EGR is the root cause of the problem but perhaps only a symptom of some other failure.

As soon as I'm feeling better, I will take your advice and clean it thoroughly... certainly can't hurt.

Further reading of the symptom charts in the Haynes book lists a faulty MAP under the "Hard Starting - Hot" section. Other matching symptom sections list possible EGR and/or MAP failure.

This seems to be the most annoying and consistent symptom of this problem... the warmer the engine, the more difficult to start. Also a strong gas smell in the exhaust once it finally starts.

Any additional thoughts appreciated. Thank-you.

 

Well, the problem with your situation is the material you are reading. I have never been satisfied with the Haynes/Chiltons line of repair manuals. I purchase a FSM (factory service manual) for every vehicle I own.

 

I actually have a set of the FSM's for this car. I just grabbed the Haynes out of convenience not thinking it would be inaccurate.

What's throwing me off is the fact that it's only hard to start after it's hot. It just doesn't make any sense.

When I'm feeling better, I'll thoroughly clean the EGR and report back my findings.

Thank-you.

 

Wow that thing was a sucker to get off... those two bolts fought me on every turn of the wrench and no direct access to the left one.

Well worth the effort however. Found two loose chunks of carbon holding the EGR open... it did not take any effort to remove them but they must have been just a little too large to blow out on their own.

Problem solved. Starts and runs just as well as it did before the original CMFI failure.

Thanks everyone.

 

Glad to hear you got the problem fixed