Top Engine Cleaner Failure - Please Help

[mmarlett]

Hello Buick Members,

I need your help.

I have an 87; GN with 34,000 miles. 8,000 of those miles have been put on in the past 3 years. Prior, this car sat for 10 years with minimal mileage put onto the vehicle.

I have followed the spring cleaning guide from the gnttype website. However, last night was the first time I performed the top engine cleaning described on that site; the cleaning were GM toe engine cleaner is put in through the intake and creates significant white smoke as carbon is removed.

However, upon completion, I went for a drive to clear out the system and had bad results. The car would studder, excellerate, knock (per scan master), pull hard, bog down, etc. I could excellerate under 3/4 throttle once, then next time the engine would break up under minimal throttle; I could barerly get the car going from a stop. While driving, it kept studering, other times it would pull ok.

Over the next hour+, I reset the computer 3 times, checked to make sure the MAF was re-plugged in correctly, and also verified that the air inlet tube from the intercooler was sealed. These were things I read as problems from other posts that had done this service.

I also noticed that, at times, my O2's were stable around 500-700. It would run with O2's remaing at 550 for 20 seconds. Prior, I remember the O2's fluctuating much more. A few times during driving, the O2's would not drop below 600 no matter the throttle position or fuel and spark adjustments I would make through the Scan Master.

Any advise on what to check next would be appreciated.

Thanks!
Matt

 

[Pronto]

Check the CC (cross counts) are moving steadly. If they are sluggish or stuck on one # the O2 is all done.

 

[lgonzalez_1986]

How is car at idle? Did you unplug maf while running and if so did idle change? If not bad maf, and as stated above check the o2 sensor is that stuff safe of these cars?

 

[mmarlett]

Thanks for the information. I am not sure how to interpret all the Scan Master readings, so your comments really help.

I did not check the CC number. I would not even know what that number tells me. I will do that and also the MAF check.

I hope this product is safe for our cars. This product was the one referenced to use by gntype.org. In addition, the GM dealer said the mechanics are always pooring this stuff into cars with great results.

 

[Boston GN]

Sounds like a bad MAF.
Mine did the same thing years back

 

[mmarlett]

The engine idled fine with the MAF unplugged and also idled fine with it plugged in. I do not recall if the rpms changed that much. I do know that it did not stall, or fluctuate the rpm too noticeably when MAF was disconnected.

Were I am confused is that the car ran well before this cleaning. Wouldn't the MAF been bad before and cause problems? Am I missing something?

Since the oxygen sensors a realatively cheap, I will try that first.

Still open for any thoughts. I will keep a list.

Thanks again!
Matt

 

[mmarlett]

What readings can I look for on the Scan Master that would indicate a bad MAF?

 

[BuickMike]

Do you use the stock intake tube? Maybe you ripped it in all of this and you are getting post MAF air in which would cause this same thing. Also, check that your plug on the MAF is in all the way. Double check all the hose clamps on all inlet pipes. Check to make sure all the couplers are on good and not torn.

Also, maybe the cleaner screwed up the o2 like everyone else stated.

Let us know what you find.

 

[theCATman]

What readings can I look for on the Scan Master that would indicate a bad MAF?

The AF reading on the SM should be in the 4-7 range, hot idle in Park.

Take it for a drive & watch the AF reading, if it increases smooth with throttle, it's probably OK. I know you said the car runs like $hit at WOT, but try to floor it & see if the AF goes to 255, if it doesn't then the MAF is shot.


Also, simple fouled spark plug(s) from dumping excess "fuel" into the engine when it couldn't handle it.

 

[Pronto]

Scroll though the Scanmaster to see the CC. Check the sparkplugs too. From what you've said about it running fine b/f it's not likely the MAF unless you squirted it through there. Crap could have gotten stuck on the sparkplugs or the O2...

 

[mmarlett]

Great thoughts! I picked up a O2 and will also look into the other suggestions tonight.

Matt

 

[lgonzalez_1986]

Check your oil. If it smells like fuel! Maybe not all cylinders mixing right! A rich plug might do that!

 

[jimski]

The plugs may be fouled

 

[mmarlett]

Well, I started tonight by checking the the Scan Master cc without changing anything. The reading was the same number, or was slow in the cc (cross count). I checked this per the earlier posting.

I also pulled one plug and found it only to be black with carbon.

Therefore, I changed the O2 sensor to a new one. Then I reset the computer. The car started, idled ok, had a few surges.

I then went for a drive and could not get 1/2 mile before it started surging. I was watching the cc on the ScanMaster and noticed the number would NOT change. When that happened, the engine would surge on the verge of quiting.

For ten minutes, I tried to get the car to just idle. Finally, the cc number rose, then stopped, and I was able to limp home.

Again, I also noticed that the O2 millivolts were always above 750-850, even at idle.

 

[getchasum]

After the use of top engine cleaner, I consider new plugs, O2 sensor & oil change a must.

 

[mmarlett]

I will get the plugs changed next. I will keep everyone posted.

Thanks
matt

 

[GNICETRY]

Tap on MAF very lightly, if you notice ANY differance in idle, even slight, then your MAF is suspect. These things are sensitive and old. Sort of like a lot of members on this board:biggrin:

 

[vacuum 6]

Sounds like a bad MAF.
Mine did the same thing years back

Yep agree

 

[chopped39]

Did you use that whole bottle? That stuff you have there gets mixed with gas in a pressurized cylinder. Only 2 ounces at a time and run through the fuel rail.The spray can stuff is the stuff you spray into throttle body and let it sit. That stuff is no longer available due to damaged catalytic converters. That stuff you have there gets mixed with gas in a pressurized cylinder. Only 2 ounces at a time and run through the fuel rail. Dodge I think still makes the spray can top cylinder cleaner. I would put in new plugs an o2 sensor. The other problem sounds like mass air problem issue

 

[lgonzalez_1986]

yep that would do it probably ruined the o2 sensor, whats your fuel pressure? bigger injectors or stock?chip, fuel pump upgraded, hot wired? if it only happens @ wot your pump might be suspect! you said idles fine and runs fine at low speeds, only at high speeds stumbles! i almost wanna say fuel filter but you did entire spring cleaning! you said car sat for 10 years did you drain gas or did you just add octane booster, if you ran entire tank fuel i would change your fuel filter again, just incase of debris on top of fuel!