At this point anything is possible. i found a website that has alot of good info about checking your timing chain - http://www.misterfixit.com/chanslop.htm

also you may want to start searching the local junkyards for a used engine and pcm, its probally going to be the easiest / cheapest fix out their, im guessing $100 for the motor and $50 for the PCM. if the timing chain checks out, i would be pionting at the cam which after breaking the engine down that far you might as well just replaced the engine, but like i said i would be looking to find someone with the same model year truck and ask them to temporally swap PCM's just to see if thats the problem. Now you said that you tried to clean the MAF but no luck correct.....i know that about half the time you can clean the MAF and it will work fine but the rest of the time it becomes damaged beyond cleaning and needs to be replaced, so if you do find someone with a pcm ask them to swap out the MAF also, it couldnt hurt right?

 

seriously?

you find an engine for that price, that isn't way high mileage, and i'll drive down myself for a spare engine.

 

yea, in syracuse here we have this junkyard that has complete engines for $125 and pcms for $35. how much are they in your area?

 

depending on the mileage, anywhere from $450 to $600 @ the wreckers.

there is this guy on Kijiji up here, that is asking crazy $$$ for this. comes as you see it.

 

I bought myself a 2002 chevy blazer xtreme 5 speed.Its all stock except for a cold air intake and a set of wheels, About 5 months ago or so. The truck ran great then started running into some mechanical issues. I had the check engine light scanned. (came up with a knock sensor and clutch sensor) First fix being the catlytic converter. Clogged. The truck lost power. But that was a easy fix to cut it off. and put in a piece of straight pipe back to the muffler.Truck ran greattttt untill about a week ago. I went to pull out somewhere and the truck fell on its face pretty much. bogging and studdering. the check engine light will flash when it starts acting up. then suddendly it powers through and runs just fine.( whats weird , is mine does worse in the city taking off and stopping. compared to running down the highway. it will run right with traffic at about 70-85 mph. Untill I shut it off again. I had it taken and diagnosed again. Coming up with a misfire code. and something else. The o2 sensor is now out. . I asked someone at another auto parts place. If the o2 sensor would do anything like the problems I am having. They told me a o2 sensor can cause multiple codes . And said that I should fix that right away. And it could possibly stop it from throwing the other codes. I have not yet got the money. But in a few weeks I should have the money to get the sensors. And send it to a garage to be checked. . I love the truck. Its good looking.Pretttty fast for a blazer. Rare. Being 5 speed. People at auto parts stores get a kick outta that. They havent seen it before...So I am realllly trying to figure out whats going wrong. Before anything tooo bad goes. ..I have the codes they pulled for my vehicle. I will find them and post it. see if its the same one or not. Any advice would help.. Thanks everyone!

 

I HAVE A PROBLEM WITH MY 90 K5 I INSTALLED A CAM VALVE SEALS NEW HEad gaskets timing chain and it runs good but when i get on the freeway it throws an engine light and stays on till i get to were im going and turn off the truck and turn it back on and the light goes away until i get back on the freeway any help!!!!!!!!!!!!!!!

 

Sorry to bring up an old thread but I am having this exact problem as Tazz9690 on my 97 4.3L. Flashing check engine light under load or 70+mph on freeway. Anyone made progress on this problem?

I have done:
Spark plugs –AC Delco Platinum’s

New NGK plug wires
Coil is new
Ignition Control Module is new
Distributor, cap and rotor are new. (cam retard is zero)

Fuel pressure is good and holds (60psi) pump is 2 ½ years old (Delphi pump)

CSFI to MFPI injector upgrade 3 years ago
Cleaned the EGR
Shimmed the crank sensor
Cleaned the MAF, it reads 4.59 g/s on the scanner
Fuel trims are within +/- 8% (no vacuum leak)
O2 sensors are new and cycling correctly
Catalytic convertor is 2 years old.
Lower intake gasket (Fel- Pro metal) just done

I removed carbon from the upper and lower intake ports


Next on my list to do is a timing chain slack test, then pull the heads.

 

Alright, here's the scoop.
Flashing CEL means your catylitic converter is experiencing extreme damage. The damage is being caused by unbured fuel leaving het engine and igniting in your cat.

No doubt you have the dreaded P0300 code to go along with it.
This code is ramdom multiple missfires. Solution for P0300 is top of the line spark plug wires and top of the line cap and rotor.

Solution for the cat is a replacement. The next thing to go wrong will be all emission realated. The cat has stopped working and is plugged up by itself. The explosions have caused the guts to become dislodged and severely reduce air flow. It will only be a matter of time before you finally make this discovery. No doubt afte you fight with it for a year.

I spent a ton og money replacing a ton of parts, only to pay the shop to diagnose my problem. Faulty cap and rotor and 2 faulty spark plug wires. All brand new parts, mid priced parts at the parts store. I upgraded to the top of the line stuff from the parts store and replaced the cat, all problem solved.

Having said all that, I do have to add this. IF your spider assemble is leaking fuel, it is no doubt being pumped into the exhaust during the exhaust stroke and ending up in your cat causing the damage. To see if it is your spider assemble, pull the top of the intake manifold off and look for the lack of carbon build up. Where it is clean is where the gas is leaking. Especially if you burn ethanol enhanced fuel. The ethanol naturally cleans the gum/varnish/carbon left by gasoline.

 

As just mentioned by Hanr3, the cap & rotor needs to be top of the line, and that means AC Delco. Don't waste your money on anything else, there is nothing better. Don't forget to put a dab of silicone dielectric grease on each terminal, inside and out, of the cap.

"Shimmed the crank sensor".... For what reason? Did you perform the crankshaft relearn after doing this? It MUST be done. If not, camshaft retard data is totally inaccurate. Which means the PCM can not accurately identify which cylinder(s) is (are) misfiring, and injector timing and ignition timing are both inacurate. The relearn must be done first, then camshaft retard.

 

I realize its misfiring. I have no check engines codes. I test the vehicle right after. I see failures in Mode 6, but I am not sure how to decipher those.
This problem has been on going for 8 years. In that time I have had 3 sets of caps, rotors, wires, and now a new distributor due to the gear of the old one being worn. I pulled each plug wire and tested with a spark test tool. No problems there.
I shimmed the crank sensor because there were marks on it from the reluctor.
I currently have an Accel cap and rotor. I will give the AC Delco another try.

Here is some of the data: