ponchomill Posted April 7, 2003 Report Posted April 7, 2003 hi everyone, I just registered. I see many driveability probs. posted here. Been wrenching for 23 years, worked in garages and ran my own for around 11 years. Now it's more of a hobby. Also Degree in Auto Tech. Can I make a few suggestions ? First thing I do with driveability/engine problems is, have the system scanned by a local trustworthy garage. I use someone I've known since high school, they have a very good machine where he works. These machines check EVERYTHING. You would be surprised at how many problems are merely wires, plugs, blocked air filters, blocked fuel filters, or fuel pump relays acting up. MANY I've found- but act much worse. Also a few things that should be checked, but SELDOM are: do a backpressure test to see if your cat. converter is blocked. This consists of removing the O2 sensor, and putting a pressure gauge in, and running the car. Over a certain pressure reading, bingo, blocked converter. It makes a BIG difference. I burned 2 valves in a Saturn 1.9 DOHC with that problem, had to pull the head ! Learned the hard way... Another is FUEL PUMP PRESSURE- we've found quite a few blocked fuel filters, and intermittently faulty fuel pump relays, and bad fuel pumps themselves. Not bad enough to stop the engine from running mind you, but below the spec for min. fuel pressure. These little problems will drive you nuts, and the car will run like crap every now and then ! One thing to remember, we are dealing with engines with computers that compensate for anything that goes wrong. If the plugs are slam ass worn out, and not firing the mixture correctly, that will create a RICH condition in the exhaust. The O2 sensor picks that up, and tells the computer. The computer in turn, LEANS OUT the mixture excessively, to compensate. End result, the car runs like shit- the computer creates a second problem while compensating, a severe driveability problem. Once the electronic spark, fuel, and emissions systems are all checked out OK, then we proceed to the mechanical possibilities. This method has shown much success in diagnosing tough problems. The key is, a GOOD diagnostic machine, with a trained operator. These machines are large roll-away units, go for around $30,000, and are updated yearly for new cars. The operators also go to school yearly to update. It is well worth the $45 to me, to have the car scanned first. Example- I overhauled a 302 Ford V-8 in a truck. The bearings were knocked out of it, down to the copper- BAD. Also a wiped cam. OK, Total rebuild. Afterward though, I drove it directly to the scan machine. The machine picked up a bad TPS sensor, and bad fuel pump relay. BINGO. That customer was headed for more problems, and would have been back. This is standard procedure for us now, scan every car. Later guys. This is a great site. I esp. like the tips for cutting the little bracket for 3.4 DOHC thermostat replacement, and the idea of using a bigger O-ring for the dist. housing leak. You guys are sharp !! Just thought I'd give some back... PS- just picked up a used GTP with 3.4 DOHC, so I'm learning too ! First chance I get, I'm havin' it scanned ! Quote
Brian P Posted April 7, 2003 Report Posted April 7, 2003 Hey, welcome! Good to have another person here with years of experience in auto repair. You've got more years experience than I (and many others here) have been on earth! Quote
Guest RedCutlassSL Posted April 8, 2003 Report Posted April 8, 2003 hey there! you bought a very good car there Quote
GnatGoSplat Posted April 8, 2003 Report Posted April 8, 2003 Welcome! I hope the 3.4 DOHC doesn't make you decide to change hobbies! Quote
NOHC_WBody Posted April 8, 2003 Report Posted April 8, 2003 Maybe buying the 3.4 will cause him to step back and have his brain scanned Quote
ponchomill Posted April 8, 2003 Author Report Posted April 8, 2003 nah, believe me, there's worse out there to work on and repair, then that 3.4 DOHC Ever put a clutch in a Saturn ?? I did- through the crack the opened up, between the trans and engine, about 3" wide...but saved me from dropping the frame. See, I'm used to it...had more shit-ass repairs on POS foreign cars too, then I care to remember....MUCH worse than the 3.4 liter DOHC For instance, a Ford Fiesta ?? What a friggin nightmare they were, had one customer with a fleet of them... Quote
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