|
Thank you for reading, sorry about the length, but I don't want to leave anything out that might help me get her going again.
About 6-months ago my '91 740 Wagon with 152k miles began to be difficult to start. I changed the rotor, distributor cap, and spark plug wires. I also checked to make sure that each spark plug was getting juice by having my wife crack it while I held the plugs near the engine block. Although this seemed to fix the problem for a day or two, it quickly returned and the car became impossible to start sometimes. Sometimes difficult to start, sometimes it would start and then stall as I began to back up, and sometimes it would not start at all. Warm or cold engine didn’t seem to make a marked difference in the difficulty in starting. After a few days of trouble starting it became impossible to start at all. Impossible is not exactly correct, because it would start if I hooked up by neighbors super-huge starting-capable battery charger to the car. The engine would turn much faster than with just the battery and it would eventually start. Once started, it would idle rough and I would have to keep it going by giving gas with my foot.
Next, I tried the fuel injectors. I took them all out and soaked them in fuel injector cleaner. I put them back and it would still take my neighbor's charger and a great deal of cranking to get it started. Once started it would idle rough and I would have to keep it going by giving gas with my foot. Not much progress toward reliable transportation yet.
Next, I had to buy another car because I couldn't fix it immediately and I needed to go back and forth to work. That was about the time I found this forum.
I then read, and read, and read. I found the diagnostic control box and tried all the tests. I also concluded that I have a Regina Rex coil, since the ignition coil is square and not cylindrical. Although it has been several months ago, I remember thinking that I found the problem. The codes indicated that the throttle position sensor (tps) was bad. I bought a new one, put it in, and adjusted it. That still didn't fix the problem.
I then though that the flame trap was dirty. It was very dirty, but was not clogged. I bought a new one, with new black plastic joint and hoses. I also found that the little medal nipple on the intake manifold was completely clogged by hard junk (the little hose on the flame trap is connected to a little nipple on the top of the intake manifold). I cleaned out the nipple. Although it would start a little easier, the idle would still go up and down and then usually stall.
Over the last couple of months, I've been able to start it from time to time and let it run in the driveway. I think I overcharged the battery and burned it up, since I was only able to crank for a few seconds before the battery would give out. I bought a new battery because I got tired of borrowing by neighbor’s battery charger and I apparently burned up the old one.
So, for the last couple of months it has only sometimes started. I have cranked it and started it a few times in the morning, at night, when humid, when cold/hot, but could find a pattern of any weather condition that made it easier or harder to start. Sometimes it would start and sometimes it would not. Once started it would idle smoothly, as far as it sounded like a consistent spark pattern was being produced. Although it was a fairly consistent bum, bum, bum, bum, bum idle, it would oscillate up and down, like it had a mind of it's own and it would usually stall after about 20 seconds. Since I didn't want the engine to sit for too long without getting warm, I had to crank the idle adjustment screw up pretty high to keep it from stalling.
This Saturday, it started pretty easily. It ran so well that I took it about five miles away to McDonalds, filled up the tank from 1/2 to full, and put some air in the tires. I should note that with the idle set really high (about 1500 to 2800) it would drive very well, it just had trouble with starting sometimes. It idled quite high and would sometimes go higher and/or drop on its own. When I got back from the store I let it idle in the driveway for a few minutes. I them gave the gas peddle a little kick to see how it sounded. After a second or two of revving from the increased fuel, it went swiftly back to idle again but this time is was much lower than two seconds before. It distinctly reminded me of the reaction of my old Volkswagen had when it was started cold, allowed warm in the driveway, and then with a quick tap of the gas it would drop the idle speed significantly. I think the Volkswagen had a spring-loaded choke.
On Sunday, I tried to start it and it would not start at all. I read the forum for about 3 hours today. I found information that made me believe that it may be the Idle Air Control Valve (IAC). I took the valve off. It is a two-wire valve and could not be taken apart and cleaned. I sprayed it good with WD-40 and put it in Diagnostic Mode 3 (Injection System Component Activation Test Mode), so it would open and close automatically, and I could get WD-40 in it while it was moving back and forth. It only opened about 1/4 inch. It definitely didn't open the entire way, but it did react to the test. It opened and closed with a tick-tock, tick-tock. I tried to start the engine with both hoses open, but it didn't start. I also got a 1-2-2 code when I tried to start it without the IAC plugged in. I couldn't get it started at all today. I tried with the iac completely removed and in all other possible combinations of it being half connected. I'll have to go buy a cheep battery charger tomorrow, so I don't kill the battery by leaving it significantly drained (it is not drained all the way now but it does turn the engine over slightly more slowly than it did before I cranked it about 30 times). By the way, how long can I charge a new batter with a 1 or 2 amp battery charger without damaging it?
I really wish I could get this 740 working again. I still have a tag on it, it is most comfortable car I've ever driven, and I would love to enjoy it some more.
Can anyone offer any help?
Thank you.
Richard.
|
