engine light started blinking when going up hills, now it is always on

I recently swapped motors with another jimmy that had less miles. Not long after the engine was installed the engine light would blink when going up hills. When I would level out it would go off. When the speed was accelerated quickly to about 70mph/120kph the light would come on again. I changed the rotor and distributor as a start and nothing changed. I then changed the fuel filter and nothing changed. I added some octane boost fluid and it got worse, now the light is always on flashing.
When it is idling in park it runs very roughly like it is really misfiring. When it is on the road travelling it still has same horsepower but light is still on. Idling is biggest problem I have. Smell of exhaust is very rich, very gasoline-like, smells like it is a mixture problem.
I had it hooked up to a code reader but the reader said that the computer in the jimmy was shot. If I replace this computer will it correct idling problems? Help, do not have much $$$ to start taking it to shops to figure out. Thanks.

Welcome to AF, what year, what engine, what codes? Then post back.

Diagnostic Trouble Codes, (DTC's) never tell you to replace a part, they tell you what circuit to check. Spark plugs and plug wires are a more likely cause for the symptoms you describe. As Maxwedge mentioned, we need more information to help you.

flashing mil light means misfire

ac delco plugs were just put in about 6 mos ago. I think the code has a 2000 in it and I have a 4.3l vortec.

We need to know what DTC's are in memory, year of the vehicle, how many miles on the vehicle. Anything you can tell us about maintenance that has been done will help too.

what are dtc's? The year of the vehicle is 95, it has been immaculately maintained. The mileage on old engine and tranny was about 350 kms, the one I put in was at about 120 kms.

1995 was a transition year from OBDI to OBDII and the vehicle could have either system. It requires the use of a special adapter to link the scan tool to the ECM in order to read the Diagnostic Trouble Codes (DTC's). If the correct adapter is not used, you may not get any codes at all, and to the untrained technician, it could be interpreted as a faulty ECM.

Okay, I have changed the spark plugs but I was given the wrong wires so those will have to wait for a bit. (I am on an island and do not get into the city too often.) One of the plugs that I had changed was destroyed! The metal part and the ceramic at the end was broken/burnt off! It was down to the nub of where the threads start, there was little left of anything sticking out past the threads. Another plug had the metal finger broken or burnt off. 3 of the others had rich deposits like gas and oil and one was fine. What would cause the plugs to do this? That may have been my problem.

I took it for a drive and the engine light stopped blinking, it blinked only when it was idling. I still have to change the wires to get a more complete diagnosis. Phew!!!

What year is the engine that is in the vehicle now? The parts place may have given you the wrong plugs last time you changed them. What plug number was in it and what plug number is in it now?

this motor is out of a '95 blazer. the old plugs were R44L TSM and the ones that I put in are RV15YC4. Maybe I was given the wrong plugs to begin with. When I changed the motor all was exactly the same so I assumed that it was the same thing that I had just changed. It didn't even occur to me to check the motor I have in now...my bad.

The AC R44L TSM plugs were wrong. The correct AC Delco spark plugs for your vehicle are CR43TS, use them! The Champion cross reference is RV12YC, which means the Champion RV15YC4 that they gave you are 3 heat ranges too hot. Leaving them in the engine is asking for trouble. It's always best to use the plugs that the vehicle manufacturer recomends.

O.k., here's what I have done...I have bought the proper parts, wires and plugs, but I am having problems with the middle plug on the driver's side. The steering column is in the way and I cannot get a spark plug socket in with an access point to tighten it. I have tried a hose and I think i have gotten it in without cross threading it but am stuck with how to sufficiently tighten it. Remember I am on an island and I cannot get a contraption to snake in there. I have a hose and have rigged it up so that it got the plug threaded but now what? hehe, island life is great!!! Thanks man.

Hey jfoxxtail,
Here is a path to follow for an easy way to get at that pesky middle spark plug:

Automotive Forums (http://www.automotiveforums.com/vbulletin/index.php) > Chevrolet (http://www.automotiveforums.com/vbulletin/forumdisplay.php?f=729) > Blazer (http://www.automotiveforums.com/vbulletin/forumdisplay.php?f=119) > How-to/Technical Info (http://www.automotiveforums.com/vbulletin/forumdisplay.php?f=2069) - How-to change the PITA #3 spark plug

or follow this link:

http://www.automotiveforums.com/vbulletin/showthread.php?t=503231

I have never tried this method but it sure does look easier than trying to wiggle your way around the steering shaft.

Good luck,
Sparky

http://www.automotiveforums.com/vbulletin/showthread.php?t=503231

I do it on every one, works like a charm! Takes about 5 minutes to remove and install the shaft. When the shaft is unbolted, and moved, the plug is right out in the open!

Alright, all done with the spark plugs and still idles rough. Light is still flashing and I have checked all the hoses. There is a really strong scent of gas and the plugs that I just pulled out (they were only in for about 150-200 kms) were a bit wet and oily too. It was as if it was almost flooding if that is possible. What to do now? Will it keep running or do I have to worry about it quitting? I am going on holidays with it and I am wondering if it will be alright. Thanks.

Check the fuel pressure. Key on, engine off, fuel pump running, pressure must be 60 to 66psi. After pump shuts off, (2 to 3 seconds) pressure must remain above 55psi for 3 to 5 minutes. Post your results.

Hey Old Master, I have just had a compression test done today and I have 2 dead cylinders!!! *!@#*!!! What to do now? Is it savlagable or should I send it to the junk yard? I just had a new engine put in out of another blazer that was totalled. Any suggestions? I just recieved a phone call to come and pick it up at the shop where the work was done. That is all I know for now.

Depends what the problem is whether to get another engine or fix this one. Need to diagnose it a little more. What were the compression readings?

The work order I recieved doesn't have the readings, just says that cylinder 1 and 6 have no compression.
I have a couple of questions: Is there much you can tell from the readings? How much work is it to fix the cylinders? Is it possible for a one-man operation to tackle the problem? Just me and my spouse are available to work on it. Do you think it will be alright to drive for a while? I got all the tools and time but need to get it about 10 hrs from here. Think it will be alright to drive that far on 4 cylinders? Thanks

no compression could be anything from bad piston rings to head gasket/cracked block or head(s) to bad valves. for it to be on 2 different sides of engine is odd, and master is right. more diag is needed.

Not a good idea to drive it, more damage might be done to it. Might want to rent a car dolly and tow it there. Did they do a cylinder leakage test, or pull a rocker arm cover off, or put it on a scope, or anything, other than just a compression test? It could even be that the timing chain jumped.

Just an idea, but is it possible that the timing chain slipped a tooth or 2? That happened to me on an old f*rd br*nc* I owned before I wised up to GM.:banghead: :banghead: :banghead: :screwy:

Hey there, the guy who did the compression test was at a GM dealer and he said that there was just no compression in 1 and 6. He did not have the results which is a bit fishy but he was adamant that the cylinders were dead. He did not pull anything to check so I am still holding out hope that it is not too major of a problem.
If 2 cylinders were gone I dont think that it would even be able to run. It runs fine after about 20 mph, cant even tell there is anything wrong except that the light blinks. Could it be that one of the sensors could be faulty? I am taking to a friend that I trust just so he could "really" take a look and see what may be wrong. I'll mention the timing thing though.
The truck runs fine except for when it is idling.

If the timing chain jumps, valve timing and ignition timing both retard. Symptons would be rough or no idle, extremely hard starting, hesitation on acceleration, loss of power, low or no compression on at least one cylinder, (and probably more than one). If RPM can be increased, the symptoms are less noticeable. There are no sensors that can affect compression. Get the numbers and post them.