EldoDave

Hi, this is my first post.

I was directed here from another forum. I was thinking this site was just for Camaro and Firebird guys but I have been told that is not the case. Hopefully there are some smart guys here who can help me.

I have an '88 Eldorado with a 4.9L and throttle body injection. What makes that unusual is that there is no such stock combination. The 4.9 is port fuel injection and the '88 Eldorado came with a 4.5L.

But the 4.5 in my car was replaced with a 4.9. In order for all the electronics and computer to work, the original intake was used from the 4.5. The TBI injectors from the 4.5 were then too small. The flow was too low. Since there is no such thing as 4.9L TBI injectors, I replaced them with injectors from a 5.0L, which I figured was close enough.

I got those injectors used, since I wanted to test out how they would work before spending the money on new injectors.

Everything worked pretty well. The car has good power. There are no engine codes. This car has on board diagnostics so I can see a lot of what is going on while driving.

The engine runs very rich when first started but once the O2 sensor warms up the car goes into closed loop and it doesn't run lean or rich. However, the idle is not very smooth. That's probably my biggest complaint. The engine runs fine when moving but the idle doesn't stay level at idle. It's in the right RPM range, but not steady.

I next tried remanufactured 5.0 injectors. That made things slightly worse. The better flow meant an even greater tendency to run rich when cold.

I next went back to the stock 4.5L injectors and modified the FPR to make it adjustable. I increased the fuel pressure but I'm not sure exactly where it is at because I don't have a throttle body fuel pressure gauge. It looks like around 13lbs on a regular gauge. Now the car is very responsive like it was with the 5.0L injectors, but the idle is still not smooth. It might help to get these injectors cleaned because they are probably original to the car.

I'm looking for ideas on what might smooth out the idle and also ideas for even better performance. I wondering if the ECM may be having issues with the 4.9L. Maybe there are parameters that need adjusting.

Any comments or advice are appreciated!

fireburdluvr85

the fueling maps are different for any given point. try the computer for a 4.9. its the same theory on why a 305 computer cant run a 350. well run it right

EldoDave

Thanks. I'm not even sure if the computer for a 4.9 plugs in. It might. Since the stock configuration for the 4.9 is port fuel injection, but I've got it set up with throttle body, I was thinking that it is way too different for the 4.9 computer to work. I can try it though, as long as I don't have to worry about shorting something out by attempting to hook it up.

dimented24x7

iTrader: (2)

The TBI board is a good place to start for info on working with the TBI. Not very often that you get the caddy guys posting, but there have been a few people whove modded those early engines. I dont recall offhand what computer those use, but I believe its a bit different than the standard ECMs used in TBI apps.

If your modding the engine, you should consider burning your own chips. See the DIY Prom board for more info. You may even want to use another computer if possible since there have only been a few people whove messed with the FWD caddy engines. I dont know if tuning definitions exist for those or not. Basically what needs to be done is the volumetric efficiency table and base pulsewidth constant for the injectors needs to be changed to bring the fueling back into line. You may also want to consider getting a wideband oxygen sensor like those offered from Innovate Motorsports. These are much more accurate than the stock narrowband O2s, which are useless for tuning.

As far as the injectors, they seldom have issues. You could probably pass small pebbles through the TBI injectors and not damage them. The likely issue in regards to the idle is the engine is just too rich. This will be a common issue when you turn up the fuel pressure to fix a lean condition at WOT. It will richen up there, but be pig rich everywhere else where it didnt need more fuel.

EldoDave

Thanks a lot. The wideband O2 sensor is something I hadn't even heard of so I did some research. I think this might be a great fix.

The 4.9 is only about 9% bigger in displacement than the 4.5. The bore is the same, but the stroke is longer. There isn't that much difference. What I have now done is gone back to the stock 4.5 injectors but made the FPR adjustable. The fuel pressure with the adjustable FPR is 12.5 lbs. I now have checked it with a throttle body fuel pressure gauge.
I still intend to try using ultrasonically cleaned injectors.

The reason I love the idea of the wideband O2 sensor is because it seems like it would compensate for some less than perfect settings in the computer, which may be a royal hassle to change. Right now, when the engine goes into closed loop, the mixture moves from rich to lean like it should. You can see it with the on board diagnostics which show the reading from the O2 sensor. You can also watch the cross counts which shows the number of times the mixture crosses the ideal set point in a certain time frame. I think it is 1.2 seconds. The higher the cross counts the better.

I can see in the diagnostics that the mixture makes a pretty big swing from lean to rich and back again when in closed loop. It doesn't stay in a narrow range. I'll bet a wideband O2 sensor would keep the mixture in a much tighter range, plus it would react right away, even when the car is cold.

Of course, this isn't a race car and I am NEVER at WOT, so I don't care about perfection at WOT, I care about normal driving range.

All that being said, the idle problem could still partially be from ignition and not fuel delivery. There could be a problem with the distributor.

ex-x-fire

Hook a vacuum gauge to the line that goes to the map sensor. Tee it in & take it for a drive, you should have a smooth needle sweep, 18" at idle.
Check your ground cables, esp. the ecm grounds. These alloy blocks can corrode at those points.
You can try advancing the ign. timing for more engine vacuum, try to avoid spark knock.

EldoDave

Is the fact that the cruise works any indication that the vacuum is good? Because if I have even the slightest vacuum leek, the cruise doesn't work. Or does the fact that even a slight vacuum leek, that I can find, causes the cruise to stop working, indicate that the over-all vacuum must not be very good in the first place?

ex-x-fire

Anytime I have a rich running problem (on a map sensor efi engine), I always check manifold vacuum. I don't rely on if the cruise doesn't work theory. Check it w/ a gauge, you can even check it w/ a vacuum pump. The reason I say check is these map efi engines, because they are sensitive to low vacuum. Vacuum tests are a good indication of a healthy engine, just like a compression test.

five7kid

iTrader: (14)

If the moderators on the TBI forum believe this to be 3rd gen related, it can live there.

Ronny

iTrader: (1)

Does it show BLM?

[QUOTEHowever, the idle is not very smooth. That's probably my biggest complaint. The engine runs fine when moving but the idle doesn't stay level at idle. It's in the right RPM range, but not steady.][/QUOTE]

I would guess lean. As I added fuel it seemed to help idle quality but waste fuel.

I wonder if winALDL supports the below? Datalogging that event would be helpful.

1990 4.5 L 16132240 def file CD1

1991 1993 4.9L 16132240 NS1

Taken off TunerPro site.

EldoDave

I would guess lean. As I added fuel it seemed to help idle quality but waste fuel.

I wonder if winALDL supports the below? Datalogging that event would be helpful.

1990 4.5 L 16132240 def file CD1

1991 1993 4.9L 16132240 NS1

Taken off TunerPro site.[/quote]

It shows INT and it is always close to 128. The engine is not lean at idle unless the car has just been started. Actually, after I increased fuel pressure I believe it can be either lean or rich when first started but after five minutes tops, it goes into closed loop and moves back in forth between lean and rich, which is what it is supposed to do. I do think the swings from lean to rich and back again might be to big. I am thinking that a wideband O2 sensor might narrow up the swing.

As for the files I am afraid that the 4.5 file is likely for port fuel injection. In 1990 port fuel injection became standard on the Eldorado. In 1991 the 4.9 became standard, so port fuel injection existed before the 4.9 did.

So here's the question of the day:

Instead of thinking about why the idle is rough can we instead list all the things that make an idle smooth??? Particularly in TBI engines?

With this list, maybe by process of elimination I will find the problem.

Ronny

iTrader: (1)

Smoothen idle?
Idle open loop(if available)
idle richer than stoich
make all cells in VE surrounding idle cell same value, same on SA.
Lock SA at idle(if available).
disallow async fueling synch only

Look at ECU and determine what part # it is.

Note 1990 is first year listed for FI far Caddy?

16132240 90 Cadillac LW2, 4.5L, V8 (ATTL) 91 - 92 Allante LQ6 4.5L V8 (AUMF

More info:
4.5An improved and enlarged version of the HT4100, the 4.5 L engine was never classified as HT4500.

Engineering allowed the company to begin increasing displacement and output again. A bored-out (to 92 mm (3.6 in)) 4.5 L (273 cu in) 4.5 version was introduced in 1988 with 155 hp (116 kW) and throttle body injection. Various versions of this engine were built from this introduction to the end of production in 1992 including a high-output LW2 version with multiport fuel injection which produced 200 hp (149 kW) and 270 lbf·ft (370 N·m) for the Allante. Outside of the Allante, Cadillac introduced a port fuel injected 4.5 L V8 engine in 1990 with 180 hp (134 kW) and 245 lbf·ft (332 N·m) across their car line up.

I find it hard to believe the car would run at all with a port fuel ECM. I bet your ECM is a earlier TBI.

EldoDave

I must not have been super clear with my first post on this thread. Only the engine itself has been changed on this car. The 4.5 was removed and a 4.9 was installed. The original intake and ALL the original electronics are still in place. Therefore, the ECM is for a throttle body injected 4.5. And, of course the car is STILL TBI.

This is the problem with finding anyone who can make any alterations to the programming of the ECM: There are files for the 4.5 from 1990, BUT that was with multiport fuel injection. It does me no good, because mine is TBI.

jwdomino

iTrader: (12)

imo the displacement diff is so low the stock ecm should be fine at compensating for the in. sounds like a tps issue maybe

Ronny

iTrader: (1)

I agree with above poster. What is the ECU #? Also what is the code on prom?

EldoDave

I agree. I have become more and more convinced that this is true. The only reason I can think of to change the ECM programming would be if I decided to use 5.0 injectors. I have tried that and it seriously confuses ECM. The car will run dead rich until the O2 sensor warms up. It also does not give enough gains to make it worthwhile. I think I have done the right thing by going back to the original 4.5 injectors and simply increasing the fuel pressure to compensate for the increased displacement. The difference in displacement is only about 9% and I can easily increase fuel pressure that much.

So the ECM should be fine. BUT there is still the rough idle problem.

About the TPS: I have checked that. You can set the position of the TPS with the on board diagnostics and it is dead on. I followed the procedure in the shop manual. It also tells how to check the TPS for smooth movement using the diagnostics and again, it passes.

I was reading yesterday in the shop manual on how to check the injectors to make sure they aren't leaking or delivering fuel when they shouldn't be. If I disconnect them and try to start the car they should not deliver any fuel. Does that sound about right? I haven't checked that yet.

I've got spare injectors I can send out for cleaning. I keep saying I'm going to do it but haven't yet. I'll try to package them tonight and get them out tomorrow.

I think I should recheck the timing too. That's kind of a catch 22. If the timing is off, the engine won't idle as good. But if the idle is bouncing around, it's hard to set the timing spot on because the mark keeps moving.

EldoDave

The ECM number is an oddball, used only on Cadillacs. The number is 1228322.

I have to remove the ECM to check the prom number. Why I didn't write it down when I had the ECM out, I do not know. It takes less than 1/2 hour to get to the prom. I'll go out and get it shortly.

Back in the day, didn't proms get updated? Like, you would go to the dealer and they would put in the latest updated prom? So maybe the car has an updated prom or maybe it's the original one. But doesn't the ECM case have a sticker on it with the original prom number?

I have another ECM from a junked car that I am holding right now. In the past I tried installing it, with the prom from the ECM that is in the car now. I was told that if you change the ECM, you still have to use the prom from the ECM you took out because that is the right prom for the car. Since it didn't help, I put the other ECM back in.

Anyway, the ECM I am now holding says "remanufactured by General Motors" on the sticker and there is no prom number on the sticker. So is this an updated ECM? Maybe I should try using it again. Would it make any sense to try using it with the prom that is in it? I know the prom number does NOT match the prom number from the ECM in my car.

My car wouldn't burst into flames on something from using the wrong prom would it? Just kidding, but seriously, I don't want to cause any damage.

EldoDave

ECM 1228322
PROM BCC AKYB

I also tried installing the other ECM I have with the prom it had. The car ran about the same as far as I can tell. That one is the same ECM number and the prom BCC is AMNP

Here's an interesting link I found. You need excel to open it.
http://www.google.com/url?sa=t&sourc...SuXNLg&cad=rja

ex-x-fire

Its only idling rough now? Try to isolate the problem by killing spark to the plugs one at a time, notice how much it changes. If you find one that doesn't change the idle, then that's the weak one.
I'm also wondering about the differences between the 4.5L & the 4.9L, as far as engine balancing. Maybe the 4.5L is internal balanced while the the 4.9L is external balanced. It could have the wrong flex plate & harmonic balancer. I'd check part numbers on those 2 things.

Ronny

iTrader: (1)

For injectors the spray should be even. Conical. No drips no sputters

I am uncertain on this one. Why would idle mark move? If idle RPM changes that should not affect the mark on balancer. Am i wrong on this? You did disconnect the plug?

From a listing ebay:
88-89 Deville 4.5L
88-89 Eldorado
88-89 Feetwood 4.5L
88-89 Seville

It appears that ECU and file is unsupported. Looks like you need to focus on mechanical.

EldoDave

Doesn't timing become more advanced as RPM increases? In the diagnostics it shows timing at 12 degrees advanced at idle. Timing was set as close to 10 degrees as I could get it in the "set timing mode". As I drive down the road and RPM increases, the timing becomes more and more advanced, like up above 20 degrees. I assumed it was supposed to do that.

So without a steady idle the engine becomes slightly more advanced when RPM increase.

One thing I just remembered: The last time I set the timing I was having issues with the idle speed control as well, which made the idle even more unstable. I have since solved that issue by installing an OEM idle speed control motor. The RPM is more stable now that it was then, so I should recheck the timing. The mark might be more steady now.

EldoDave

The balancer was on the engine so I'm pretty sure it is right.

I will try killing spark as you suggest. Most of these basics will be redundant as these are the first things I checked. I replaced plugs, plug wires, cap, rotor. I set the gap to what it should be. UNLESS the 4.9 should have a different gap than the 4.5....

The plug wires were ordered online. I researched several sites and forums to see what users thought were the best plug wires, so they are supposed to be really good. That was last year and I threw out the box so I can't tell you who makes them off the top of my head.

I have had issues with plug wires on another car. I put new plug wires on my Aurora and it ran terrible. It was kicking out codes related to the plug wires. I took them back to the auto parts store and got another set. A BETTER set. SAME PROBLEM. I then went to a u-pull junkyard and pulled an OEM set off an Aurora. They gave them to me for free. Problem solved. To this day, you can hardly tell the car is running and it has 240,000 miles on it.

Ronny

iTrader: (1)

Yea I was brain dead on that Q. As you open throttle you will see SA advance at timing mark.
But is dist wire to ECU dicsonnected? Dist is then esentially locked and idle cannot wander unless parts are worn. Only other factor is Vac. So I would check VAC. Many times I fould a vac leak but the idle was just higher not moving.

Possibly IAC? There is a plug to block IAC. Also it can be cycled fully closed and then disconnected. Easier to place a plug. I use a foam hearing protector. Place in IAC opening at IAC. Now no IAC control. It will decrease RPM as IAC is tpically 10--20 steps so make sure engine is warm. See if idle is then stable.

I fouled a plug this spring. Did not affect idle much but lost power.

EldoDave

IAC...IAC..
I don't think there is one. There's an idle speed control motor and they are prone to have issues. I think IAC came out later. The idle speed control motor works fine. Just don't ever buy anything but Delco on these because aftermarket are junk.

The distributor wire to the ECM is not disconnected. If it were, it would set a code. I have had it get disconnected and it did set a code.

I'm going to check several things that have been discussed when I get home from work today. Thanks for all the help. I really do appreciate it.

OH, i suppose I should have mentioned by now that the pollution control stuff is not on the car. I think they call it the air management system. There were tubes that ran through the air management valve and to the exhaust manifold and the air cleaner. The tubes are removed from the car and the manifold holes are plugged. There is also a little tube coming off the the CAT and that is plugged too. The CAT is NOT PLUGGED. It is new. No codes are set by this stuff being removed. The holes where the hoses entered the air cleaner are plugged too.

Ronny

iTrader: (1)

Can you monitor voltage to ISCM ? Is it like overreacting. Like over shooting the correction to idle speed? Or stall saver on asking ISCM to react and it over shoots command?

Does it have a throttle stop screw? If so can you disable ISCM and use it to set idle speed?

EldoDave

Ronny you're thinking of everything! Unfortunately, again I have an answer. LOL.

You can do an ISC override in the diagnostics and make it retract all the way so it is effectively doing nothing. Or you can get it to a place you like and unplug it so it acts like a throttle screw. I've done both. And....you know the rest. It didn't help.

By retracting it all the way you can check the minimum idle speed. Basically, checking to see if the throttle screw is set right. It is.

EldoDave

Well, the spark plug wires just became very suspect. Numbers 1 and 3 are junk for sure. When you put a timing light on either one they double fire but only on the plug end. Up by the distributor they are fine. It turns out they have been rubbing against a bracket next to each other. This did not wear through the coating and just put a slight crease in them. In my book, if they can't handle that, they are junk to begin with.

I put tape around the #1 wire and rerouted it and it fires OK now. #3 is still misfiring. Tomorrow I will check them all and then decide whether to just replace the bad ones or change them all. Changing them all kind of sucks. I'd first just like to get rid of the obvious misfires and see how it idles then.

Funny thing is, the diagnostics does not check for misfires. When I hooked a code reader up to my Aurora it told me exactly which cylinders were misfiring. No such luck on the old Caddy.

ex-x-fire

This was a requirement when they went to the OBD2 systems. The newer engines w/ crank sensors can pick up misfires where the older distributor engines can't. Ecms are alot faster too.

EldoDave

Here's the latest: #3 was indeed still acting up with random misfires that looked like both over firing and misfiring. #7 was showing random misfires as well. I didn't check the back wires. I pulled plug #3 and it looked OK. The plugs were almost new, but for some reason I installed Autolite platnums. I pulled them all and replaced them with ACDelco plugs. I carefully checked the gap on each plug.

Now I can detect no misfires with a timing light! All wires have been tested.
The engine idles much better, but...It's still off a bit. The RPM bounces around a bit. You can see it with a timing light on the timing mark, you can hear it, and you can see the actual RPM on the driver information center.

This is not caused by the idle speed control motor. My guess is, it is either a slight vacuum leak or clogged injectors. I should have ultrasonically cleaned injectors in my hands some time later this week.

Thank you to those who have helped. This thread has helped steer me away from the ECM and focused me on mechanical things.

One more thing: I replaced the two questionable plug wires with stock ones from the junkyard. I grabbed all eight plug wires from the junkyard but only used the two. I did an ohms test on all those wires plus the two that I removed. The junkyard wires averaged 4500 ohms per foot. The wires I removed checked 2900 ohms per foot, so they are actually better wires. The #3 wire may not have even been bad because the plug was causing misfiring there. The #1 wire must have been damaged by rubbing the bracket and that was my fault. So these are actually probably really good wires.