KHE Posted December 19, 2004 Report Share Posted December 19, 2004 You need to perform the fuel pressure test while the symptoms occur. The fuel pressure gage you buy will most likely have a 12" hose which is useless. You need a 4-foot hose on the gage so you can tape the gage to the windshield while driving. Your symptoms sound like a bad ignition component. It is still hard to believe that with such low mileage. Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Scotty Posted December 19, 2004 Author Report Share Posted December 19, 2004 You need to perform the fuel pressure test while the symptoms occur. The fuel pressure gage you buy will most likely have a 12" hose which is useless. You need a 4-foot hose on the gage so you can tape the gage to the windshield while driving. Your symptoms sound like a bad ignition component. It is still hard to believe that with such low mileage. Kevin wouldn't a bad ignition component set a code, even an engine misfire code? While it 'feels' like ignition, the engine seems starved, it will BOG BIGTIME and then all of a sudden the engine comes to live and revs. Hopefully I can buy one of those guages inexpensively, Thanks, Mike Link to comment Share on other sites More sharing options...
Scotty Posted December 19, 2004 Author Report Share Posted December 19, 2004 Checked the fuel pressure today and at idle it was 38 to 40 psi, and when I accelerated the engine it peaked to 60. Disconnected the battery, and cleaned the ground off the negative battery cable. Still bogging badly. I still need to check the 3 rear plugs and check the ignition cables. No codes. Mike Link to comment Share on other sites More sharing options...
KHE Posted December 19, 2004 Report Share Posted December 19, 2004 You need to perform the fuel pressure test while the symptoms occur. The fuel pressure gage you buy will most likely have a 12" hose which is useless. You need a 4-foot hose on the gage so you can tape the gage to the windshield while driving. Your symptoms sound like a bad ignition component. It is still hard to believe that with such low mileage. Kevin wouldn't a bad ignition component set a code, even an engine misfire code? While it 'feels' like ignition, the engine seems starved, it will BOG BIGTIME and then all of a sudden the engine comes to live and revs. Hopefully I can buy one of those guages inexpensively, Thanks, Mike A bad ignition component will not always set a code. Back in September, my '96 Seville began to stumble on acceleration and I discovered that 6 of the 8 plugs were missing the platinum pad. The resulting gap was 50% more than the factory setting. No codes were set. I wouldn't suspect plugs at your low mileage but they are worth checking if anything, just to rule them out. Were you checking the fuel pressure while driving the car so you could note the pressure when the bogging occurred? Kevin '93 Fleetwood Brougham '05 Deville '04 Deville 2013 Silverado Z71 Link to comment Share on other sites More sharing options...
Scotty Posted December 19, 2004 Author Report Share Posted December 19, 2004 You need to perform the fuel pressure test while the symptoms occur. The fuel pressure gage you buy will most likely have a 12" hose which is useless. You need a 4-foot hose on the gage so you can tape the gage to the windshield while driving. Your symptoms sound like a bad ignition component. It is still hard to believe that with such low mileage. Kevin wouldn't a bad ignition component set a code, even an engine misfire code? While it 'feels' like ignition, the engine seems starved, it will BOG BIGTIME and then all of a sudden the engine comes to live and revs. Hopefully I can buy one of those guages inexpensively, Thanks, Mike A bad ignition component will not always set a code. Back in September, my '96 Seville began to stumble on acceleration and I discovered that 6 of the 8 plugs were missing the platinum pad. The resulting gap was 50% more than the factory setting. No codes were set. I wouldn't suspect plugs at your low mileage but they are worth checking if anything, just to rule them out. Were you checking the fuel pressure while driving the car so you could note the pressure when the bogging occurred? Kevin, I pulled the front three plugs and the gap was .065 and it should have been .060. I need to pull the rear three. I am not sure if these are platinum plugs or not, I will post the AC number, I did not see pads on these.. The tip is different than I have ever seen, very tiny point is that a sign of platinum? As you mentioned I only found a guage with a short hose, so I could only test it at idle and with the idle racing high, do you think its possible that I can race the engine and it will show 50 to 60 but in drive it could mess up? I am thinking of cutting this hose and adding an extension to it with brass fittings and hose clamps, I just need to find the right hose This problem is frustrating. Next I plan on pulling the rear three plugs and checking the ignition wires. This problem boarders on tranny related its as if once the car is in gear tremendous friction is hauling the engine to its knees, I wish it would set a code. It does not want to accelerate and holds back its very odd Link to comment Share on other sites More sharing options...
Scotty Posted December 19, 2004 Author Report Share Posted December 19, 2004 It takes an AC 41-940 plug Link to comment Share on other sites More sharing options...
Scotty Posted December 20, 2004 Author Report Share Posted December 20, 2004 It takes an AC 41-940 plug, according to the AC Delco site this is a Platinum plug. The picture on the AC Delco site shows that it has a pad on the electrode. The first three plugs I took out did not have a pad..... Can the lack of a pad cause the problem that I am having? My wife did say it was beginning to use more gas.. Link to comment Share on other sites More sharing options...
Scotty Posted December 20, 2004 Author Report Share Posted December 20, 2004 It takes an AC 41-940 plug, according to the AC Delco site this is a Platinum plug. The picture on the AC Delco site shows that it has a pad on the electrode. The first three plugs I took out did not have a pad..... Can the lack of a pad cause the problem that I am having? My wife did say it was beginning to use more gas.. Can missing platinum pads on the plugs cause serious driveability problems? Link to comment Share on other sites More sharing options...
Oldgamer Posted December 20, 2004 Report Share Posted December 20, 2004 ...While it 'feels' like ignition, the engine seems starved, it will BOG BIGTIME and then all of a sudden the engine comes to live and revs... Trying to analyze what's going on... If engine all of a sudden comes to live it nothing to do with plug gaps or something like this by me. I remember when I had have a bike it always was a water when symptoms were like this. Despite the nice pressure, still if you got a water in a pipe, problem will be there. The gauge will show you correct pressure of what? Fuel or water? I don't know if it possible to check some how what you got in a pipe. Is it possible to disconnect (carefully!) fuel pipe somewhere and pure some out to check it? I don't know may be it sound stupid, but I beleive sometimes "old grandfather' methods" can bring amazing results. No codes, problem intermittent - so it looks like water in a fuel pipe. Link to comment Share on other sites More sharing options...
Scotty Posted December 20, 2004 Author Report Share Posted December 20, 2004 Good Thought, I thought the same thing, that is why I put in HEET extra duty dry gas and let it sit over night. It may make sense to pump out some gas and let it sit to see if there is any water in it. Maybe another container of HEET... Thanks, Mike Link to comment Share on other sites More sharing options...
Phillip Posted December 20, 2004 Report Share Posted December 20, 2004 Everything you have described still points to ignition. It takes a very severe misfires to set a code. In some cases, you don't get a misfire code until the plug is disconnected. I had similar problems with a 3.8 l chev and it turned out to be a plug wire that leaked causing carbon tracks on the plug. Because of the location, you could not easily see the arcing. Good luck and be patient, the answer is out there. Phillip Link to comment Share on other sites More sharing options...
Scotty Posted December 20, 2004 Author Report Share Posted December 20, 2004 Everything you have described still points to ignition. It takes a very severe misfires to set a code. In some cases, you don't get a misfire code until the plug is disconnected. I had similar problems with a 3.8 l chev and it turned out to be a plug wire that leaked causing carbon tracks on the plug. Because of the location, you could not easily see the arcing. Good luck and be patient, the answer is out there. Phillip Thanks Philip, I plan to buy a new set of plugs and test each ignition wire for resistance.. Thanks, Mike Link to comment Share on other sites More sharing options...
Scotty Posted December 22, 2004 Author Report Share Posted December 22, 2004 MARIKA!!!! You were RIGHT!!! The Chevy service manager called and after telling my wife that he was impressed with all the work and diagnostics I did, he said she was 95% sure it was a clogged CAT!!! He said I saved him a lot of time and diagnostics! LOL He has not confirmed that yet, but you were the first to respond with a cure and it looks like you were right! He has seen clogged convertors before! WOW Thanks, Marika Link to comment Share on other sites More sharing options...
Marika Posted December 22, 2004 Report Share Posted December 22, 2004 MARIKA!!!! You were RIGHT!!! The Chevy service manager called and after telling my wife that he was impressed with all the work and diagnostics I did, he said she was 95% sure it was a clogged CAT!!! He said I saved him a lot of time and diagnostics! LOL He has not confirmed that yet, but you were the first to respond with a cure and it looks like you were right! He has seen clogged convertors before! WOW Thanks, Marika You know what made me think of it? Did you ever see the movie Beverly Hills Cop? The scene where Axel Folley sticks a banana in the tailpipe of the undercover cop car and how the car reacted was what made me think of the answer to the problem....LOL!!! Am I warped or what??? LOLOLOL!!!!!!!!! But anyway, I hope the problem gets solved soon and good luck, Mike. If you really want to make people safe drivers again then simply remove all the safety features from cars. No more seat belts, ABS brakes, traction control, air bags or stability control. No more anything. You'll see how quickly people will slow down and once again learn to drive like "normal" humans. Link to comment Share on other sites More sharing options...
Scotty Posted December 22, 2004 Author Report Share Posted December 22, 2004 Its comfirmed, it was the CAT, and they replaced it for NOTHING under warranty! So I went out and bought a fuel pressure guage and code reader for nothing.... WELL for my toolbox!!!! Yea more tools!! Thanks, Marike! I should have listened..... So after all of the below, the extreme BOGGING on acceleration was the CAT, let that be a LESSON LEARNED: 1. Bought CODE READER, there are NO codes being set. 2. Checked transmission fluid, 3. Changed Fuel Filter, 4. Changed Air Filter, 5. Bought new Coil pack and swapped in to all three positions, 6. Checked Fuel Pressure at Schrader valve, fuel pressure is 38 to 40 PSI at idle and increases to peak at 60 when engine is revved. The hose on my gauge was not long enough to check the fuel pressure during driving conditions, 7. Added one container DRY GAS in case there was water in the tank, 8. Pulled 3 front spark plugs and checked, gap was .065 re-adjusted to .060, the platinum pads were missing on front 3. I plan to replacing the plugs soon, I did not get a chance to check the REAR plugs or wiring Link to comment Share on other sites More sharing options...
Marika Posted December 22, 2004 Report Share Posted December 22, 2004 I'm glad your problem was finally solved. In a positive light, you certainly learned a lot about cars in the last few days..LOL!! If you really want to make people safe drivers again then simply remove all the safety features from cars. No more seat belts, ABS brakes, traction control, air bags or stability control. No more anything. You'll see how quickly people will slow down and once again learn to drive like "normal" humans. Link to comment Share on other sites More sharing options...
Scotty Posted December 23, 2004 Author Report Share Posted December 23, 2004 I'm glad your problem was finally solved. In a positive light, you certainly learned a lot about cars in the last few days..LOL!! This one had me really stumped. I think I took the correct paths. On the bright side, it is difficult to diagnose the CAT being the problem in such a new car with only 37K miles. I think we all learned something on this OT problem... Thanks Link to comment Share on other sites More sharing options...
Oldgamer Posted December 23, 2004 Report Share Posted December 23, 2004 I'm glad the problem resolved too. But you're right, how come CAT get clogged under 37K? It looks strange to me. Link to comment Share on other sites More sharing options...
Scotty Posted December 23, 2004 Author Report Share Posted December 23, 2004 I was thinking that I may have missed a symptom that could have pointed me to the CAT/exhaust restriction. I hooked up a vacuum guage to the engine and it was reading LOW at idle. Normal is around 20 inches of vacuum according to the guage and I was running about 16 inches . I was thinking (after I heard the CAT was clogged) that if exhaust can't get out, the engine won't create as much vacuum... Any thoughts? It's an old vacuum guage so I assumed it was related to the car being a V6 and that the V6 doesn't draw as much vacuum as the old V8s.. Can anyone add to this line of thinking regarding vacuum...? Thanks Link to comment Share on other sites More sharing options...
Oldgamer Posted December 23, 2004 Report Share Posted December 23, 2004 ... I was thinking (after I heard the CAT was clogged) that if exhaust can't get out, the engine won't create as much vacuum... Why you did think so? It's not like current circuit. When piston (I'm not sure I use right terminology) goes down and "suck" the air intake valve is opened, but exaust valve is closed which separate intake vacuum from exaust pipe. So, despite clogged exaust, engine still will suck air. Link to comment Share on other sites More sharing options...
Scotty Posted December 23, 2004 Author Report Share Posted December 23, 2004 ... I was thinking (after I heard the CAT was clogged) that if exhaust can't get out, the engine won't create as much vacuum... Why you did think so? It's not like current circuit. When piston (I'm not sure I use right terminology) goes down and "suck" the air intake valve is opened, but exaust valve is closed which separate intake vacuum from exaust pipe. So, despite clogged exaust, engine still will suck air. From some of the research I did, a clogged/restricted exhaust will decrease vacuum.. as a matter of fact the materials that came with my vacuum guage stated that also.. see this link: http://www.misterfixit.com/cat.htm Link to comment Share on other sites More sharing options...
Scotty Posted December 23, 2004 Author Report Share Posted December 23, 2004 By the way this is a good example of a GOOD OT thread that benefits our knowledge!! Link to comment Share on other sites More sharing options...
Phillip Posted December 23, 2004 Report Share Posted December 23, 2004 I am glad you found your problem and I am glad you shared your experience with us. This is one to be filed away for future reference. I am surprised it was the Cat, but that is a difficult diagnosis. I think that the trail you followed was logical and sensible. The tools you purchased will be valuable additions to your tool box the next time you need to do some diagnostics and the other work is good maintenance anyways. Further, your service guy sounds great. I have never had a mechanic pay any attention to the diagnostic work that I have done. This guy sounds like a keeper. Phillip Link to comment Share on other sites More sharing options...
Scotty Posted December 23, 2004 Author Report Share Posted December 23, 2004 I am glad you found your problem and I am glad you shared your experience with us. This is one to be filed away for future reference. I am surprised it was the Cat, but that is a difficult diagnosis. I think that the trail you followed was logical and sensible. The tools you purchased will be valuable additions to your tool box the next time you need to do some diagnostics and the other work is good maintenance anyways. Further, your service guy sounds great. I have never had a mechanic pay any attention to the diagnostic work that I have done. This guy sounds like a keeper. Phillip Thanks Phillip! Yea it is a hard one but not a new one. WHen I was in college I had a 66 Caddy Conv, that would not start and when it did start it was weak... My friend was a service manager in a Caddy dealer and they used to have a long resonator under the drivers seat that used to rust and collapse and obstruct/restrict the exhaust. Well to make a long story short, I took a hacksaw to it..... and it was not the problem... it was a timing chain.... Link to comment Share on other sites More sharing options...
Oldgamer Posted December 23, 2004 Report Share Posted December 23, 2004 Thanks for a link! Link to comment Share on other sites More sharing options...
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