88 now running smooth!

[KDirk]

Just as an update to my post a week or so back about my 88 running rough. I wanted to post this is it may prove useful to others down the road.

Here is what I found after doing a tuneup with little or no improvement in the way the engine ran or in the fuel economy which was very poor.

First, I found the ECM had been replaced with a salvage yard part. The ECM itself was correct, but had the wrong MEM-CAL in it. I want to thank Padgett for sending me a ROM image of the 1988 ANCX EPROM by email, I was able to burn a new PROM yesterday and get that fixed. This eliminated my chronic E024 code (VSS circuit problem) as the car is now running the correct "program".

Then changed out to a known good Delco ICM and coils, ditched the Magnavox (good riddance). But, it was still running rough. Found that cylinders 2&4 were dead, based on the ECM injector override. After much frustration and some cussation that probably scared the neighbors, I made a maddening discovery. The 88 final edition FSM has a mistake (who'd have guessed?) in that it lists the left bank of cylinders (nearest firewall) as odd, and the right bank (nearest radiator) as even. Wrong! Looking at the fuel injector plugs (which are numbered by cylinder if you look closely) reveals that it is exactly opposite of that.

Rerouted my spark plug wires and shazaam! Now it runs like it was meant to. Nice and smooth, plenty of power and decent fuel economy. The real kicker is that it was mis-wired when I bought it. Like a doofus, I replicated the order of the wires when I did the tuneup and ICM/coil change over, even checking the manual to make sure it was right. I didn't suspect the manual was wrong until I got desperate for lack of any other explanation. This also proves the 3800 is a beast, in that it still ran enough to move the car at highway speeds on 4 cylinders in the wrong firing order.

So, I just wanted to let anyone interested know that it is fixed, and how. I know a lot of regular contributors here get bugged when a thread ends with no follow up or resolution. This one has a happy ending, and a good lesson to be learned: trust your instinct and don't believe everything you read.

KDirk

[padgett]

Well, it was just the injectors that were misfiring so each cyl had the right amount of gas and the plugs were firing right. Back in the day, the Rochester FI used by Chev and Pontiac was a "constant flow" mechanism and I remember one paper saying the right amount of fuel was more important than when it is added to the mix. The injectors were aimed to point at the back of the intake valve.

Of course that was before pollution and lean burn engines so guess it makes a difference now.

Glad you found it.

[Jim]

There are a lot of really good people on this forum like Padgett and Ronnie and others who are so willing to help others keep their cars on the road and running correctly with no compensation for themselves.

Thank you to all of you.

A thought popped into my mind as I was reading Padgett's post. Never put old gas into a fuel injected car. It can clog the injectors and cause weird temporary problems.

A while back I put some old gas from a Reatta parts car into my 2001 GMC pickup. It was about 2 gallons mixed with the about 12 gallons already in the tank. We drove around for a while and one time when I shut the engine off and came back later to start it it would not turn over. After a while it did turn over but started and ran poorly for a minute or so. The same thing happened once more. What had happened is one injector was sticking open from the bad gas and because the ignition fires two cylinders at the same time, the correct one and one other, the wrong cylinder was firing when it shouldn't and pushing that piston back downwards when it was trying to come up.

[Guest Mc_Reatta]

So the incorrect EPROM program was the cause of the problem with the speed display on the CRT output?

Good catch on the errata in the 88 FSM for the cylinder numbers, but ALL the FSMs say the same thing. "Starting at the front of the engine, the cylinders in the left bank are numbered 1-3-5 and the cylinders in the right bank are numbered 2-4-6". OOPSIE!

Proper firing sequence is 1-6-5-4-3-2|1-6-5-4-3-2 (your fuel delivery)************ \***\*-*\

you had wiring for******2-5-6-3-4-1|2-5-6-3-4-1 (your spark delivery)

Can't get this table to line up right...

So you were probably running so-so on 6-4-2 since they got spark just after they got fuel and somewhat on 1-3-5 since they had to wait 4 clicks for the spark to catch up with the fuel.

Edited May 30, 2011 by Mc_Reatta (see edit history)

[Guest steveskyhawk]

I think Kevin should be included in the "really good people" list and I believe he is one of the most knowledgeable people on this forum. I'd like to see Kevin be a technical adviser for the Reatta Division.

[padgett]

Don't forget that there are only three coils so two cyl fire at the same time: 1&4, 2&5, 3&6. firing order is 6(3)-5(2)-4(1)-3(6)-2(5)-1(4). Also from time immemorial, for GM the driver's side is the left side. (this was confusing in a 1970 Pontiac FSM so nothing new). I always thing radiator side odd, firewall side even for a transverse engine unless in a Fiero then firewall side odd and then there are Corvairs...)

[KDirk]

Padgett,

Correct that GM considers the drivers side left, for purposes of referring to which side of the car they are talking about in service data. Basically viewed as one would be sitting in the drivers seat, so to speak.

As MC quoted from the FSM though, it states [paraphrasing somewhat here] that as viewed from the front of the engine (pulley end on any engine I've ever seen) left is 1-3-5 and right is 2-4-6. Now, irrespective of what GM considers the left side of the car, the left side of the engine would (logically) be the left side as viewed head on from the pulley end of the engine. At least that is how I read it based on how the FSM phrases the passage about the cylinder order. This remains true of course even if the engine is transversely mounted. Thus, as written, it would be left (firewall odd/right (radiator) even. So, it is my opinion that the FSM is either very poorly worded or just plain wrong in this case.

Apparently, someone else who worked on the car previous to my ownership read it the same way which likely explains why it was wrong and why I had a heck of a time figuring out why nothing I tested checked bad, and nothing I repaired or replaced improved how it ran.

This is yet another case which called for the "KISS" method: [K]eep t imple tupid! Many times a problem like this results in chasing non-existent problems and causes much aggravation for the person doing the troubleshooting. Sometimes the stupidest answer is the right one.

Oh, and MC, yes the PROM was the entire reason the VSS data was not being picked up by the ECM. The 88 has the VSS routed first to the ECM and then retransmitted to the BCM by a dedicated line, whereas 89 on had the BCM pick up the VSS first and resend it to the ECM (exactly opposite of the setup in the 88). I believe you were the one who pointed this out in my previous thread on the subject, so thank you for your insight on the matter.

Now, I don't know what car this PROM came out of (was marked "ASSS 1293" on the sticker, definitely not any year or variation of Reatta, I checked all codes valid for the 4 model years both Federal and California emissions versions, that was not on the list) but it was apparently from an 89 or later 3800 equipped vehicle of some sort.

Also, there are no longer any MEM-CAL's for the 88 stocked by GM SPO anywhere that I could find, even searching other dealer inventory nationwide. If anyone needs an ANCX PROM for an 88, drop me a line as I can burn one if needed, since they can no longer be bought [new at least].

Thus ends this chapter in Reatta madness.

KDirk