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BLM =150??!!!


Guest trofeo73
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Guest trofeo73

Upon trying to determine why my car is running so poorly these days, I noticed that the BLM on the screen does'nt vary much from 150, I understand that that is baddddd. Maybee to rich? The car has been progressivly getting worse,,,,starting up then running verrry rough before dying, then after starting up again it runs ok. The car lacks so much power it wont turn the tires over anymore, and it still smells bad from time to time. However,, After a fast trip though Oklahoma for 4 hours it ran 50% better after starting up up after it sat for 5 minuites. If only I can trace it down, the car would be so much more of a pleasure to drive, any thoughts???

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Good running BLM (block learn mode) should be in the 125-130 range (ideal is 128). What is your instantaneous reading ? <P>Lots of things can cause, is it running bad immediately on cold start or after it goes closed loop ?

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Guest trofeo73

I am not sure what you mean by instantaneous reading but while driving it it will go from 145 to 150. Here are some notable things:<P>At 75mph it will stay around 145. <P>The car runs bad at cold start, if the ac is on when starting it will likely die. <P>Also while being followed by a friend, he noticed a VERY STRONG sulfur smell and black smoke while drivng behind me... At that time I was at WOT and going 70. <P>I have done the tune up and checked many things. I noticed that the EGR valve leaked smoke out of it when I ran a can of sea foam through my car. Maybee it is the cause of a vacum leak.<P>I noticed that the ecm is a remanufactured unit, not the original. <P>the Prom ID reads: APTN<P>One more thing, After driving 75 for 4 sustained hours through Oklahoma I noticed that it ran great after staring it up when it had sat for 5 minuites...<P>What do you think???????

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Sounds like a vacuum leak or crack/leak somewhere in the exhaust ahead of the O2 sensor. Does the fuel integrator read high also? The fuel integrator is sort of the short term adjustment to try to get the BLM back to the ideal of 128. There are quite few vacuum hoses, some visible and some that are kind of hidden to the rear of the throttle body and are fairly close above the exhaust crossover. It doesn't take much of a leak to fool the O2 sensor into thinking it's lean. Your comment about the EGR possibly leaking sounds like a good place to start in any case.

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Do not have a APTN dump so cannot check. Agree is sounds like you are running rich because ECM thinks you are lean Integrator is "Instantaneous" I was referring to. Runs good on startup because is not closed loop yet (timer delay). <P>Unfortunately there are a lot of things that could cause - marginal O2 sensor, coolant sensor, MAF sensor, etc.<P>Best way to troubleshoot is with a PC or recording scan tool that can take a "snapshot" of all readings while running bad and at a fixed speed/condition.

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Guest trofeo73

I think I will take it somewhere that specializes in that, I did some looking around and I could not find a vacum leak. I determined that the EGR was not at fault. I dont have the tools to check "everything", though I wish I did. Hopefully an honest shop can help me. thanks

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Guest trofeo73

One observation that I noted is that cracking the throttle from idle quickly in gear or in park results in the BLM to go back down to 128. I reset the computer by diconnecting the batery hoping to see what the computer does. It read 128 for little while, but then started to creep back up to 150 as it "learned". I think I am one step in finding the culprit.

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Guest trofeo73

Update!! I noticed a small exhaust leak near the o2 sensor, (by the down pipe). I attempted to plug it with jb weld and it does run a little better. Also I noticed the EGR valve, and a spot on one of the exhaust ports leaking exhaust smoke. I was able to notice it while running some sea foam through it. It causes the engine to smoke very bad for a short time, which in turn reveals EVERY concievable exhaust leak. In the service manual it says that an exhaust leak can cause air to be "sucked" in causing the o2 sensor to "see" too much air. I bet it is even more true if it is before it. I am going to replace the manfold with a carefully inspected new one. I will keep you all posted, Any thoughts?????

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I think you are on the right track. Vacuum or exhaust leaks will cause exactly what you are looking at. When the exhaust pulse passes the crack it causes a low pressure area behind it and pulls air in. The stock engine does not use exhaust manifold gaskets but they are available aftermarket, and may help if the flange is warped, or you could have it machined flat. Have you tried tightening the bolts at the head? It is not unheard of for the manifold to crack, although this design is a lot better than the ones on the turbo 3.8's, which cracked with regularity. If it is the rear manifold, it isn't a lot of fun to remove and you will need to rotate the transaxle fill tube out of the way (but do not pull it all the way out). It's also a good time to open up that rear exhaust outlet. If you look inside, you will see the restriction.

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Guest trofeo73

Ok, here is what I found: A bolt on the far left of the manifold was gone!!!!!!! So,, I replaced it with a new one. That helped clear some of the smoke when I tested it with sea foam The EGR still leaks exhaust and there is a crack in the TEE where the manifold and the downpipe are welded on. This is les than 1/4 inch from the 02 sensor!!!!!! And... it still leaks. I will correct all of this VERY soon by spot welding and checking bolt tightness. Hopefully this will help things out. Tell me what you all think about pluging the EGR tube. 140 dollars is alot of money for somthing that is to me, worthless and bound to fail.

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I suspect plugging the EGR will lead to some engine knock, which will cause the computer to pull timing. The purpose is to decrease combustion temperatures during different driving modes. It shouldn't operate at idle and at full throttle, and it seems to be modulated fairly well with the three different size ports, so driveability is good. If the valves close properly, you could just disconnect the electrical connection and see what effect it has, although it will probably set a code. As for the gasket, I got a new one with the FelPro set when I overhauled the engine, so it must be available, although it may be part of a set. If you can find a sheet of compressed asbestos you could probably make your own. Not as good as the metal foil sandwich but would give at least temporary relief.

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Guest trofeo73

Would the hole in the exhaust cause it to run rough when cold, I thought the computer would'nt care until it got to closed loop operation. I found a gasket for around a buck, but I it is the valve that is leaking, I guess I need to get a new one... frown.gif" border="0

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Before closed loop is achieved, the hole shouldn't bother the O2 sensor but it doesn't take long to reach operating temperature in warm weather. If the EGR is indeed leaking, especially internaly, it can certainly cause a poor idle and low speed performance.

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