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I've posted on this subject prior, 'Flat spot' upon acceleration at mid to high range load. Sometimes near 30 mph, and sometimes at higher rpm. A plethora of problems was listed on the service sheet. However, not any were valid. Service sheet specified, 1. EGR VALVE and Gasket (EGR Valve has Vacuum Leak) 2. Carburetor base gasket cracked 3. Air Filter housing temperature switch/ sensor leaks 4. Engine vacuum tank along left inner fender leaks and 5. Cruise control servo has a vacuum leak "Caution Noted" to inspect spark plug wires and plugs.
We could not find any of the faults listed, nor any vacuum leaks (Estimate total) $2671.72. So, after service check at American Speed, they said they could not find any faults with the items marked as 'defective'. I was still having the problem so I decided to toss in a quart of MMO and have gone through three tanks with Gumout Carburetor cleaner. Put on about one hundred miles with the MMO. The last two days, the car has run flawlessly: Rochester Carburetor 4 Barrel kicking in, Overdrive excellent, seems as the idle is better. No issues at the moment. I'm actually stumped and amazed. I cannot determine what to do nor can I assess any faults. The cap, rotor, plugs, and wires are within range; about 30,000 miles. Changed all the filters: Manifold, Air Breather, and that Round Filter in the emission tank, along with the Air cleaner element. Have not changed the EGR as yet, nor the carburetor fuel filter. * The motor has not been timed in over twenty years, if not more.
I would very much appreciate any opinions associated with the aforesaid.
Last edited by synoptic12; April 29th, 2022 at 06:15 PM.
Year, model, engine, transmission, mileage any relevant history please. It sounds as though the MMO may have cleared a restricted/gummed passage in the carburetor.
Year, model, engine, transmission, mileage any relevant history please. It sounds as though the MMO may have cleared a restricted/gummed passage in the carburetor.
1986 Oldsmobile Cutlass Supreme Brougham 5.0 Liter (307 Vin Y.) (200 transmission -3 Speed) 166,000 Miles, I added the MMO to the oil, not gas tank. The car is fully documented from first day of purchase. What do you mean, 'relevant history'? Thank you very much for the reply.
Tough to diagnose from here. It could be the lock up solenoid sticking on at times. It could be the TPS starting to die as well. It could even be the EGR valve sticking. Even the O2 sensor could be getting lazy. A voltage meter is your friend. Start by checking for proper TPS operation, Key on, Engine off. Also check map sensor function with it running. An EGR, purchase a vacuum pump to test it for leaks. An O2 can also be checked with a voltmeter. Your car is 36 years, parts wear out. The problem is tracking down the issue, which often don't pull a code, early EFI was the same. A factory service manual is a huge help, they have flow charts to track down running issues. Good luck.
Tough to diagnose from here. It could be the lock up solenoid sticking on at times. It could be the TPS starting to die as well. It could even be the EGR valve sticking. Even the O2 sensor could be getting lazy. A voltage meter is your friend. Start by checking for proper TPS operation, Key on, Engine off. Also check map sensor function with it running. An EGR, purchase a vacuum pump to test it for leaks. An O2 can also be checked with a voltmeter. Your car is 36 years, parts wear out. The problem is tracking down the issue, which often don't pull a code, early EFI was the same. A factory service manual is a huge help, they have flow charts to track down running issues. Good luck.
* Did you view the estimate in the foremost entry? There is no mention of any sensors that you make mention of listed. The mechanic looked at the vehicle and conducted all the tests.
I've replaced the Oxygen Sensor, Catalytic Converter. I have the factory service manual. The 'dealer' assured me that it was not a sensor. Yet, I place no credence into what they stated. In fact, the dealer stated it was the Catalytic Converter, but it was not. I have an Egr which I'm going to replace as well as the carb fuel filter. If it were the TPS or Lockup solenoid, would that be sporadic? The problem is that no one will work on the car due to the age and there are not many, if any than can be of any use. If it were a 'sensor' as to the: TPS, MAP, or Lock up Solenoid, how would you explain the current run state as being excellent? Thanks very much for your help. I'm not really good at checking sensors, so I may bring it to a mechanic I know but really do not wish to go there.
Last edited by synoptic12; April 30th, 2022 at 07:18 AM.
Your car has the Computer Command Control (CCC) engine management system released by GM in 1981. It will run well when tuned exactly; however, to tune it exactly requires a couple of special tools, a service manual and a technician experienced in the CCC system. The dilemma is going to be finding a qualified tech willing to work on the car. One of the worst moves at this point would be to allow anyone to work on the car who doesn't KNOW that system. Spend time and search out an older, experienced and qualified tech.
In the interim I'd try a fuel system cleaner such as Techron, BG or LubriMoly.
Yes, the TPS can be sporadic. Is the check engine light illuminated? The lock up is usually just stuck on or doesn't work at all. The cracked carb base is a definite concern, if causing a vacuum leak but should be constant. It looks like he diagnosed the EGR valve. EBay probably will have a replacement for it. The cruise servo can be fixed with RTV. Coat the the whole visible servo area. The replacement servo are no longer available for many of our old cars. It will probably fix your cruise, if it isn't working. Really 4 bent rims? Did the previous owner drift when they parked? How do they look? Some looks questionable but it does show you have to search for many parts for these old cars. Good luck.
Last edited by olds 307 and 403; April 30th, 2022 at 07:51 AM.
If the engine has not been properly tuned in 20 years, I'd start there. In another thread you praised Tasca for taking good care of your car with their top notch mechanics. Can't they figure this out?
If the engine has not been properly tuned in 20 years, I'd start there. In another thread you praised Tasca for taking good care of your car with their top notch mechanics. Can't they figure this out?
I remember that literary exercise (thread) down a rabbit hole that went no where.
* Did you view the estimate in the foremost entry? There is no mention of any sensors that you make mention of listed. The mechanic looked at the vehicle and conducted all the tests.
You're asking questions on a board that has members well versed in cars such as yours. But then asking to compare notes with a "professional mechanics" opinion....
Unless the mechanic is old school they will bleed you out financially. Modern mechanics generally hate working on cars like ours ...
RWD Oldsmobiles are way too old for perpetual easy answers. Whether it's a 1988 or a 1968. Sometimes you have to go over and through everything with a fine tooth comb. In order to find the issue or issues.
Yes, the TPS can be sporadic. Is the check engine light illuminated? The lock up is usually just stuck on or doesn't work at all. The cracked carb base is a definite concern, if causing a vacuum leak but should be constant. It looks like he diagnosed the EGR valve. EBay probably will have a replacement for it. The cruise servo can be fixed with RTV. Coat the the whole visible servo area. The replacement servo are no longer available for many of our old cars. It will probably fix your cruise, if it isn't working. Really 4 bent rims? Did the previous owner drift when they parked? How do they look? Some looks questionable but it does show you have to search for many parts for these old cars. Good luck.
I'm the original owner. No check engine light. There is 'no' cracked carb base: checked it with American Speed. The servo works fine; nothing wrong there. I'm not concerned with the wheels. However the dealer that serviced the vehicle made no mention of it. Not really a big deal. I'll most likely replace the EGR which I already have (Standard) and replace the carburetor filter which not any have made mention. The symptoms of a clogged or bad carb filter can cause the above issue.
If the engine has not been properly tuned in 20 years, I'd start there. In another thread you praised Tasca for taking good care of your car with their top notch mechanics. Can't they figure this out?
Tasca is 'history'. They refunded me approximately $2600.00 for their more than disreputable work.
You're asking questions on a board that has members well versed in cars such as yours. But then asking to compare notes with a "professional mechanics" opinion....
Unless the mechanic is old school they will bleed you out financially. Modern mechanics generally hate working on cars like ours ...
RWD Oldsmobiles are way too old for perpetual easy answers. Whether it's a 1988 or a 1968. Sometimes you have to go over and through everything with a fine tooth comb. In order to find the issue or issues.
Good luck !
Thanks very much, most appreciated. I agree with you.
Yes, the carb filter could be plugged and definitely could be starving it. Whoever removes it, hopefully they hold the housing with a 1" wrench and use a 5/8" flare nut wrench and don't twist the line. Every Olds V8 I have, came to me with a twisted line at the carb. Some mild, some pretty bad.
Any possibility that a sticking valve (Any Valve including Exhaust) would cause a flat spot? Right now, the car is running tops. Could MMO have solved the problem.......... Or three tanks of the Gumout ? Opened it up, 4 Barrel Rochester is whomping.
Last edited by synoptic12; April 30th, 2022 at 07:07 PM.
Sure, why not? The most likely thing is what was done last. Internet troubleshooting is difficult, especially when the issue goes away.
The only thing that was 'done last' > MMO and three tanks with Gumout in each fill-up. I really hate to test each and every part, just painstaking work. Well, if the engine continues on the same course as it is now, that is a real mystery. The engine is still pulling at top speed, idle is much improved. I'm still changing the carb filter and EGR. The AC Delco wires are good as are the AC Delco plugs. All new filters. I cannot find any frayed or worn emission hoses. The DC cap and rotor are in range of mileage but I'm changing out those as well. I'm giving it more time to see if the problem returns. Again, if not, I do not know what to say. I really do not even care to do top end work any longer. However, I'll eventually get there, when I get the urge. Thank you very much for the input.
I hope you didn't pay that estimate above. Most of that estimate is **** and they were trying to bend you over.
Glad car is working. This is acting like something was gunked up in carb. Be happy.
I'll agree with you on your synopsis. "NO" I did not pay for the estimate. The car was returned because Tasca switched out the new parts I gave them and substituted rusted nuts and bolts (Yellow Zinc too) (Catalytic Converter). Enclosed are some pictures. Furthermore, Tasca charged me $2400.00 for a break job and wheel bearings, spindle replacement and front end alignment. They used 'Dorman' junk and there is still a snap in my right front wheel. Brought it back three times and still not corrected. Filed two complaints with the AG for the State of Rhode Island (Peter Neurona). By the way, I was ready to file suit but all funds were returned, about $2600.00. What Tasca did not know is that all my phone calls are logged and recorded. Rusted Nuts NEW NUTS and Bolts Magnaflow Converter Yellow Zinc (Trickery) Backside Old Sensor Removed
Last edited by synoptic12; May 1st, 2022 at 05:12 AM.
This whole post just screams "what not to do"
DON'T take your "classic" (pre-OBD II) car to ANY dealer for service
DON'T expect techs trained on computers to know anything beyond what the computers tell them
DON'T supply shops doing work with parts
DON'T sue someone over your own lack of foresight (see 1-2)
1.) The first (Mechanic) was well versed in 'Classics' at the dealership. That is why I went there. He left to the 'truck center' to make more money.
2.) The second or next technician was allegedly versed in older cars. However, that was a farce.
3.) The dealership stated for me to obtain the parts for they (Service Adviser) said it was too much work for them.
4.) There are many snakes in the grass in this generation. That is why they have courts and laws. I will bring a civil suit against anyone trying to deceive me AND I proved it here. It has nothing to do with 'foresight'. Trust is the key whereas there just are not any adhering to this principle in this era.
5.) Please do not lecture me, I've done paralegal work for many years.
*Did you see the rusted "Nuts" they used. I provided them with Hex Flange Bolts and Nuts, Black Phosphate Oil, Grade 9.5. You have and know not the entire facts.
It really makes no difference, for I'll continue in the same approach to any; just waiting for them to deceive me.
Last edited by synoptic12; May 1st, 2022 at 06:30 AM.
Black oxide fasteners rust, fairly quickly, I will add. What they installed appear to be cadmium plated, a characteristic usually found on SAE grade 8 hardware. BUT, you're smarter than i, so you do you, boo.
There's a really good Quadrajet guy in CT, but I wouldn't wish you on him as a customer.
Last edited by fleming442; May 1st, 2022 at 07:31 AM.
[QUOTE=oldcutlass;1424578]It may have been the bolts you provided were too short.[/QUOTE
LOOK HERE: https://classicoldsmobile.com/forums...-160521/page2/ "NO" Definitely "NOT". The bolts were O.E.M specifications. In fact I have a thread somewhere on this forum with the O.E.M. sizes. The hardware I provided were 'Locking Nuts' whereas the person (Technician) most likely did not wish to go through the trouble. Furthermore, the car was brought back to the 'same' place to have the right hardware installed. So, you're wrong. Needless to say, my logged calls can corroborate all their deeds verbatim. They were caught 'red-handed'.
Last edited by synoptic12; May 1st, 2022 at 01:39 PM.
I took the car for a ride today and opened up the motor. After kicking in the overdrive at about fifty-miles an hour, the motor really picked up speed. Moving faster to 80 mph, the motor was asking for more: 'still pulling'. It was like there was extra air and six jets instead of the 4 (Quadrajet). I really can't understand it. I'm at a loss to explain it. The only thing I did was use Gumout in three (3) consecutive tanks of gas and I added the MMO in the oil. I put on about 100 miles with the MMO. Can this possibly be? All input here is very much appreciated.
Thanks very much. I did not get the mass improvement until I added the MMO. I'm sticking with that product for sure. At the next oil change would you use conventional or semi-blend synthetic oil?
Valvoline VR-1 10W-30 conventional oil with zinc for flat tappet cams. Or similar.
I have hydraulic roller lifters and valves.. I've been using the 'Valvoline' semi-synthetic blend 10W30. Should I stay with synthetic or go to Regular Conventional oil? Should I lubricate the heat riser?
Last edited by synoptic12; May 2nd, 2022 at 01:44 PM.
Ok, then normal 10W-30 is fine, no zinc needed. Whichever you want on the oil type, the engine will not care. Marvel Mystery Oil is not meant to be used long term. Take it out on next oil change (no hurry) and leave it out.
That lube will burn off first time the car is run. Check and see if the valve is working or not. When cold and the car is off, the valve should be open. Hook a hand vacuum pump to the line, give the vacuum motor vacuum and see if it actuates. It usually either works well or is rusted stuck. If it's working, no need for lube. If it's not because it's rusted, it might be too far gone for the lube to help.
Ok, then normal 10W-30 is fine, no zinc needed. Whichever you want on the oil type, the engine will not care. Marvel Mystery Oil is not meant to be used long term. Take it out on next oil change (no hurry) and leave it out.
That lube will burn off first time the car is run. Check and see if the valve is working or not. When cold and the car is off, the valve should be open. Hook a hand vacuum pump to the line, give the vacuum motor vacuum and see if it actuates. It usually either works well or is rusted stuck. If it's working, no need for lube. If it's not because it's rusted, it might be too far gone for the lube to help.
Thanks very much, most appreciated. If you have time, actually what is MMO? Whatever it is ' it worked', worked like a charm. Some have said that it was just a thin oil with additives. However, I would not know. There is consensus, even from Marvel that you can put it in your gas tank. I have always used Gumout for over thirty years. Would MMO be of any benefit in the fuel? Again, thank you very much for the courtesy and support.
April 29th, 2022, 06:04 PM
'Flat Spot- 'Bogging Down'/ Stumped > Opinions
