Reatta Died

[Guest Durahansolo]

Alright, the 89 has been acting up since right before winter. It has been hard starting for awhile and as each day passes it does things that are more strange than the last. A few months ago I was pulling up in front of my church. Usually when I get there I pull up in the driveway so I can back out and park on the opposite side of the street. This day I drove the car up the driveway where there is a incline and the car went dead. As I slowly backed out of the driveway I realized it was dead so I restarted it and it immediately died again. Started it up again, skipped church and drove straight home. The next morning it started right up like nothing was wrong and I drove it to work all week. The next Sunday the exact same thing happpend and it died in the church driveway incline then immediately started back up. I had been getting a EGR error on the screen for awhile so I asked my dad to clean it and he did that about 2 weeks ago. It drove a little better so I decided to replace the spark plug wires since they haven't been replaced since I bought the car. Today was the first day I've driven it since replacing the spark plug wires, I drove to work and it drove good. When I left work for lunch I drove to the mall and got out, when I got back in 30 mins later it started up extremely rough and died when I switched gears. After that I spent about 15 mins trying to get it running again so I could get back to work.

I think my original possible causes were: the Fuel Pump, Coil Pack (Upgraded Version) or the fuel filter. My MPG dropped way down, used to be 17ish but now its down to 12, I think its partially because a few of my tires might be low. On the way home I'm planning on grabbing a fuel pressure tester so I can try to rule that out.

Adding in something else, the past few days it seems like it doesn't have any umph or push to it for the first few minutes, then after I've driven it for a bit, it picks up. I was thinking possibly the Throttle Position Sensor? I mean it'll be going pretty slow and then when I turn up the gas on it, its like it won't even register, but as I ease my foot off the petal, it'll pick up more than it did when it was down.

Something else I wondered about, the upgraded coil pack I have has a Ground wire hanging off of it that we had connected to the battery. Is that wire not supposed to go there?

[Guest Drake]

Check the tailpipe. If black and sooty inside, oxygen sensor might be acting up, but should set a code. Also, you should be able to check the proper function of the EGR valve through your CRT. You said your dad cleaned and seemed to run better. Might be going south.

The ground wire on your ICM conversion, I'm not familiar with. I've got the original on my 89. I'm sure someone else will chime in shortly.

[harry yarnell]

Bad TPS should set a code.

Don't forget about a possible bad crank sensor. This WON'T show a code.

[padgett]

1) What do you mean by "upgraded coilpack" ?

2) Do you still have the original ICM (Magnavox)

3) Failing but not failed O2 sensor will kill MPG - will show up in BLM reading.

4) What brand/model of plugs and what gap ?

5) Were the new plug wires at least 8mm ?

What you describe (push on gas a lot, not much happens. Push a little and more) could be a clogged fuel filter, failing fuel pump, or open pressure regulator but will show up in a pressure test. Water in the gas will not (add alcohol).

The sometimes good (particularly at first and bad later) is characteristic of an ICM (75%) or secondary ignition (25%) issue.

Stalling when you take your foot off the gas but immediately restarting is usually a dirty IAC.

Just some places to start. Doesn't sound like anything major. If you were close, we'd just toss a Delco and some gauges onnit.

[Guest Durahansolo]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: padgett</div><div class="ubbcode-body">1) What do you mean by "upgraded coilpack" ?

2) Do you still have the original ICM (Magnavox)

3) Failing but not failed O2 sensor will kill MPG - will show up in BLM reading.

4) What brand/model of plugs and what gap ?

5) Were the new plug wires at least 8mm ?

What you describe (push on gas a lot, not much happens. Push a little and more) could be a clogged fuel filter, failing fuel pump, or open pressure regulator but will show up in a pressure test. Water in the gas will not (add alcohol).

The sometimes good (particularly at first and bad later) is characteristic of an ICM (75%) or secondary ignition (25%) issue.

Stalling when you take your foot off the gas but immediately restarting is usually a dirty IAC.

Just some places to start. Doesn't sound like anything major. If you were close, we'd just toss a Delco and some gauges onnit.

</div></div>

1. We upgraded the coil pack to a Delco with the Padgett swap like last january. I figured somebody would ask if I had done that or not

2. Pretty sure its been gone for awhile.

3. We replaced the O2 Sensor probably last August I'll check that next.

4. Pretty sure the plugs are Delco, I'll have to find out what the gap is.

5. New wires were 8MM.

Cleaned the IAC once last year probably around August. I'll look into those suggestions over the weekend since it'll be somewhat nice outside those days.

EDIT:

^^That's the wire that was connected to it when my dad pulled it. He asked me about it but I'd never seen anybody mention it on the boards here before so we decided to just leave it on there.

[Guest CL_Reatta]

or maybe god is trying to tell you something???? lol....

Well last ash Wednesday (08) I was driving to church, and was going way out of my way to, big snow storm and everything, on the way there got hit by another car (his fault) didn't go to church after that.

[padgett]

Wire normally goes on the 3/8 stud under the ICM mount but must be removed to get to the third nut on the ICM (I usually leave that one off).

BLM is a giveaway to an O2 issue, shouldn't be over 135 except at idle/0% throttle (goes max then). When my Bosch began going away I was getting 14 mpg in town and BLM was reading 150+. BTW the sensor needs to be completely ded before codes will set, if just mostly ded it won't (but Miracle Max won't save)

New one added about 4 mpg & BLM dropped back to nermal.

Occasionally my local U-Pull-It has a 2 for 1 sale, I look for nice coilpacks then.

Harbor Freight has good sales, the fuel injection pressure gauge is often under $10.

[Guest ekvh]

What does BLM stand for, Padgett?

[padgett]

In Colorado it is the Bureau of Land and Mines. In GMese it is the Block Learn Multiplier - the ECM determines the pulse width - amount of gas injected into the cyl as a function of rpm, load, temperature, TPS, and a few others.

When in closed loop the the O2 reading is used to generate two "fudge factors", the "Fuel Integrator" (BD19)- short term changes (seconds) and "Block Learn Multiplier" (BD20) which holds long term corrections.

If everything is right both FI and BLM will read 128. If the O2 reports a lean mixture, then the ECM will increase FI and then BLM to richen it up. More means more fuel. Under about 135 is normal, above generally indicates a failing O2 if everything else is working properly.

Just replaced the O2 in my coupe: BLM was running 148-150 at 45 mph and was getting 14 mpg in stop and go driving, now it is reading 132-134 and getting 18 mpg under the same conditions. This was a Bosch O2 sensor that only had a few thousand miles on it. I replaced with an NTK.

This gets asked often enough that it should be somewhere permanent.

[Tinker]

Here's a list of ACRONYMS related to the Reatta and most all of GM ECM's.

And here is an explanation of how "FUEL MANAGEMENT" works inside the ECM .

[padgett]

Good site but a little confusing as are most. A "first generation" O2 sensor as used in the Reatta is reliable only at one point, stochiometic or about 14.7 parts air to one part fuel (by weight not volume). At this point it puts out .45v (450 mv). When rich the output goes higher, lean it goes lower. It is not accurate even there until it reaches about 600F so there is a delay before going into closed loop.

Sensors are now in their third or fourth generation since (heated, wide-band planar sensors) which are much more accurate and more expensive.

Hokay so what the ecm looks for is transitions - periods when the reading crosses the midpoint - and the average values which are interpolated (want 11-12:1 for power and 15-17:1 for economy cruise). Too much gas only hurts MPG while too lean can burn things. Also remember what I said about only being accurate at 14.7:1 ?

So the engineers at GM created a set of "maps" or "best guess" as to the proper mixure for any speed. The biggest variable is the injectors - sets are matched but usually in three or more groups - rich, neutral, or lean. Outliers are not sold. The ECM is expected to do fine tuning.

Now with a detected bad O2 sensor, the ECM reverts to open loop and makes an educated guess which is garenteed to be too rich (safe answer) and mpg plummets. This usually occurs when the sensor stops transisioning (what "cross counts - ED18 - are about. This often happens at idle so that is a special case.

The problem occurs what the sensor "partly fails" which often happens if it becomes clogged (waaay to rich a mixture will do it) or poisoned.

Where most descritions get confusing is in how they decribe the values. Many say 128-150 means lean. What they really mean is that when you see a high (above 128) FI or BLM reading the computer has detected a lean condition (O2 below .45 more than above) and is richening up the mixture to compensate. If the O2 detection is false and the mixture is not really lean then the computer is commanding it to go over rich which kills gas milage (but that is the safe answer).

[Guest Durahansolo]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: CL_Reatta</div><div class="ubbcode-body">or maybe god is trying to tell you something???? lol....

Well last ash Wednesday (08) I was driving to church, and was going way out of my way to, big snow storm and everything, on the way there got hit by another car (his fault) didn't go to church after that.</div></div>

Haha, my dad thought and said the exact same thing when I told him about that.

Ok, decided to go ahead and have the filter and the fuel pump replaced since my dad knows a guy that works on those. Guys worked on it and fixed it yesterday and somehow one of my rear brake lines broke. The line was extremely rusted and probably was going to break off anyways so it was good it fell off there. They also installed a new brake line in the rear. My dad had replaced a bunch of brake lines when the system broke about 2 years ago but that one was the only one that he didn't replace. The car ran great to work this morning, also picked up about 7MPG so I'm at 19.5MPG. The real test will begin when I leave work to go to lunch, if it starts right up then the problem is fixed. Still going to look at the oxy BLM test.

[Guest dantm4]

My 1990 is doing the exact same thing yours did. It took me a while to replace the fuel filter (figured I could do that instead of the shop) and when we went to move it back into the garage the rear brake line broke. Not sure if I should try and fix the line myself or not, but was going to get the fuel pump changed before the line broke.