Spoke to soon / Rough idle back

[Guest imported_blazer1997]

Happy New Year Everyone.

I thought my problem was solved. Nope. Again at idle in park some rough idle, but in drive become real noticeable.

This list of items I have replaced.

1.Plugs

2.Plug Wires

3. Manifold Gasket

4 PCV Valve, and grommet

5.Fuel Filter

6 Cleaned egr replaced 2 gaskets

7 Thermostat

8.IAC Valve

9.Clean, and de-screen TB

10.Maf

11.Replace Oxygen Sensor

12.Replace gas Cap

13.Injector Cleaner (Lucus)

Today used long screwdriver, and could hear 2 strong pinging from each injector.

Then while at idel removed the harness from each injector, and engine really started to miss.

Could a injector still be bad at idel but perform after acceleration?

Could the fuel pump be bad?

Could it be the fuel pump regulator?

I have removed every ground connection I could find, and cleaned each one.

Need help guys this one is above me. <img src="http://forums.aaca.org/images/graemlins/confused.gif" alt="" />

[padgett]

Any chance you have another 3800 you could swap the ignition module and coils ? You could be having a weak spark (worst case is in o/d lockup up a slight grade at 50 mph).

Along those lines, do you have the original Magnavox ignition (square 3in1 coils) ? If so where were the new plugs gapped ? (Spec calls for .060" but I have not seen a Magnavox fire reliably over .045").

[2seater]

A check of the fuel pressure will give you a better indication of the condition of the fuel system. If the pressures are where they should be it will help determine if the regulator is doing its job and if the pump is suppling enough pressure. If the pressure remains reasonably stable for a short time after shutdown it will give some indication of a leaking injector. I do not know this for a fact, but it would seem reasonable a bad spray patterm from an injector may show up in the idle or low speed performance and would tend to be covered up at higher engine speeds? If these are the Bosch 901 injector, they have multiple holes for the outlet, so it could be possible to have only partial flow, and the ECM can only compensate for the entire engine, not one or two weak ones. It is also possible the coil pack or ICM may be weak. I again do not have direct experience, but several people on several different forums indicate a smoother idle with the later style Delco coil setup. By the way, you can turn the individual injectors on and off from the diagnostic system in the overide mode. You can also ramp up the idle with the IAC overide, disconnect it and then turn injectors on and and off to do a crude cylinder balance check. If nothing turns up, you might want to check the cylinder compression or have a leakdown test done. These engines are pretty robust and usually do not have a lot of internal problems.

[Guest imported_blazer1997]

Still running the Magnavox 3 in 1 coil but was replaced in 2004. Auto zone employee pulled each plug from the coil and there a strong spark for each plug wire.

Not able to give brand on the injectors same one when I purchased this vehicle, but thinking as you are maybe 1 or 2 weak injectors causing the problem at idle. The throttle response in drive or park is instant no hesitation at all, and still getting 29 to 30 on the interstate.

What brand of injectors would be considered? Think this is the GM # 25531465 for 89 Reatta. Price from GM direct is $83.31 each little high.

[Guest alex_houston]

When I had that issue it almost drove me crazy. Sometimes ran great but usually slugish and rough. Then out of frustration one day I swaped out the ecm. No problems since.

[Guest TommyH]

im no engine expert, i dont know much, but could it possibly be the harmonic balencer? i was reading about these engines, and why it was important. just a thought

[Guest imported_blazer1997]

Part # for ecm, and cost? Thanks

[Guest alex_houston]

I can't help you there. But expect very costly if you intend to buy new. I am too cheap so I always get from parts cars.

[Guest F14CRAZY]

I'd try a used one if just trying it out. Usually about $60 at salvage yards. Can come from like any 3800 powered car of the time period (they should cross reference for you). Remember to swap the "memcal" from your old one to the new one.

[Guest imported_blazer1997]

Ck again and showing no codes, but engine exhaust is extremely rich while at idle in garage. Had garage door open.

F14crazy stated to swap the "memcal" from the old ecm to new one. Where is it located? inside the ecm what does it look like?

Thanks

[padgett]

Is blue, about 3.5" long and under the removable (2 screws) cover on the top of the ECM. Is a lever on each end - push and MemCal aka CalPac aka PROM will unlock and eject.

Over-rich is common when engine is cold, should clear when system goes into closed loop (about a minute after engine start).

BTW, full throttle is not very hard on an ignition, only winds to 5000 rpm, is quite rich (in Power Enrichment phase), and each coil only fires two cyl. Misfire is most likely at hot idle and at light throttle (in cruise) on a slight grade at 50 mph in lockup o/d.

Used ECM is $40-$60 and is good to have a spare. It is unlikely that the PROM will be for a Reatta but most can be reprogrammed so good to have a spare of those also.

ECM should have a sticker on top with 1228253 or 16198264. Rebuilt from FLAPS should be under $100. New from GM is p/n 88999198 and will probably be slightly over $100.

--------------

If replacing the ignition with a later Delco (three individual coils, $25-$40 for everything - plate, ICM, coils - as one piece from yard) it is best to get a 91-94 Riviera/Regal/Reatta unit from a 3800 since it has the right mounting plate (flat, three studs sticking out the bottom).

AFAIK GM is still using the same ICM and coils on new 3800s, just the plate is different.

[Roadster90]

<img src="http://forums.aaca.org/images/graemlins/smile.gif" alt="" /> ... ICM, ECM as mentioned/suggested X 2 in your previous thread... (not rock solid or guarnteed, but simply from multible previous experiences...Hal / Two Seater will possibly attest).....

Anyway, have we "all" forgotten the best thing this forum has seen (F 14, I am surprised <img src="http://forums.aaca.org/images/graemlins/smile.gif" alt="" /> ) as far as one of ... or better stated, the best, most reliable and resonable used parts suppliers, not taking into account his integrity, and so on? JIM FINN ? Just reminding <img src="http://forums.aaca.org/images/graemlins/smile.gif" alt="" /> .....

Good luck with your problem...

[2seater]

Injectors rarely actually go bad, but it is possible to have a buildup causing failure to close or maybe a poor spray pattern. Before I would start replacing them, I would have them professionally cleaned. My preference is to remove them and have them done in a reverse flush or ultrasonic cleaner but they can be done on the car using a different method. You can also purchase reconditioned injectors for about 1/4-1/3 of the cost mentioned, or brand new Accel 19# injectors for $30-$35 each in a set of six. As pointed out in several other posts, a rough idle can have many causes. The hard part is trying to narrow the search as much as possible without buying a bunch of expensive parts. It would seem that at some point, you did have the problem solved, at least temporarily, so it seems likely you may have already found the problem area, or somehing closely related, such as new plugs or wires helping a weak ignition?

[D-a-n-i-e-l]

compression test?

tps?

cps?

O2 sensor?

diffrent EGR, I believe our EGRs use coil to acctuate and old coils can act verry odd

[Guest imported_blazer1997]

Today made a visit to junkyard found ecm with same # 1228253 for $31.42. Installing it tomorrow 01/03/07 see what happens.

Going back for the later Delco individual coils.

[Guest imported_blazer1997]

Reading another post regarding ECM. Question? Since I found a ECM with the #1228253 do I still have to change the prom from the reatta ECM to the one I just purchased? I guess blue chip inside the ecm is the prom?

Thanks

[padgett]

If the original, the four letter PROM code will be on the outside. If not or to be sure, remove the cover and look at the top of the blue MemCal. There are two "windows" and under one there will be a grey silver sticker. The code will be on the sticker.

Chances are it will not be a Reatta PROM but can be reprogrammed. Incidently I can use a couple of extras and suspect Ryan could also.

[Machiner 55]

Here's a source injectors and injector cleaning. Haven't used them but phoned them for info and were prompt, courtious and helpful.

[Guest imported_blazer1997]

Thanks for the info on the PROM.

Injector source is very helpful. Thanks give them call tomorrow.

[Guest imported_blazer1997]

Going back next week pick up couple ECM. Cost will be 31.42 + tax $1.89= $33.31, and shipping cost.

No extra charges. Let me know Mr. Padgett by 01/10/07.

Thanks Larry

[Guest imported_blazer1997]

Switched ECM same problem. Pulled coil pack off to replace with another one had on hand, and noticed the gel substance has lot of bubbles. Could this be causing idle problem.

Went to search couldn't find anything.

[Guest Mike_s]

FWIW I've used "high" concentrations of Techron every so often to clean the injectors, remove combustion deposits,, etc., I now use it before changing plugs because the plugs seem to take a beating from using it. I'm wondering if the Lucas cleaner may have affected your plugs?

Which brings me to this question? Have you pulled the plugs to look for odd coloring, which may indicate if there's a problem with a specfic cylinder(s).

[2seater]

The potting material surface should be relatively smooth and firm. If it looks like it is melting, it probably is, and indicates a defect or overheating.

[Guest imported_blazer1997]

Could the potting material surface cause the rough idle that having???

[Guest Mike_s]

No,

If the potting material surface looks as if it's melting, it's probably due to overheated\failing electronics burried in the pottimg compund.

[D-a-n-i-e-l]

how many miles does you engine have?

if the ecm rout does not work I would go back to engine basics. ie checking plugs for odd coloring (mike_s) and compression, and you said it is running rich at idle (sure sign of bad rings)

have you checked fuel pressure? and the regulator?

[Guest imported_blazer1997]

Next step. Sending off injestors to be tested, and cleaned. Company is cruzinperformance.com

this gentleman seems to really know his stuff with all new equipment. Let everyone know after get them back. Also thanks to everyone with their feeback regarding my problem.

[Guest imported_blazer1997]

Sent my injectors off to Cruzin Performance and waiting for UPS delivery 01/22/07. Let everyone know if this solved my problem.

[olbuickman]

Blazer 1997, Last fall I was having the same type of problem with my Reatta. I had my favorite Buick dealer pressure clean my fuel injection system . I could not believe all the crap that was coming out the exhaust. I spent $60 and the tech spent close to an hour going through the system . I could not believe the difference the way the car ran and still does after the cleaning. I had tried using techron FI cleaner in the gas but it still didn't get the job done.

[Guest imported_blazer1997]

Well this morning the brown truck arrived UPS with my flow tested, and cleaned injectors with new o-rings, and inlet screens from cruzin performance.

Finally after replacing almost everything I have a smooth idle.

Thanks to all with their advise. Larry

[Guest F14CRAZY]

great to hear you've got it taken care of. I will have to remember this fix