Replaced Crank and Cam Sensors: Still Dying

[HotZ28]

Thanks Bob, I was thinking the same thing!

[BNaylor]

Originally Posted by HotZ28

Thanks Bob, I thinking the same thing!

Hi Bo,

No problem. I hate getting confused. Makes our job harder. Later.

[Smith1000]

Hey, Where'd it go? This works fine for me.

I just came in from working on the Lesabre. It seems it needs a new alternator. If I have it in drive, sitting in the driveway (emergency brake on) with the lights, radio, heater on, and I shift it into Park, the idle (rpms) will adjust with the shift and then the alternator charging drops down temporarily to less than 12 volts. The tach/idle begins to decrease. After about 6 or 7 seconds, it recovers and charges normally. It has not died while doing this (this evening).

It sounds as if the alternator has a little rattle or jingle to it. I think, at low idle, it begins to lock up, slowing the engine down. It then will recover. I think, when going down long hills, when the idle drops and the alternator slows, it catches and locks up occasionally, slowing the engine and killing it on occasion. At any rate, it definitely needs an alternator to solve the charging problem and that may solve the dying problem (it did not die this evening). I get the same volt reading at the battery and the alternator.

I checked the vacuum lines and they are good. No leaks at the power booster. I did find that the throttle body nuts were a little loose. If I sprayed carb cleaner on it, it would increase the idle slightly. I tightened 2 of the nuts, but could not get to the 3rd. I will try to tighten it tomorrow. The 2 I tightened solved the slight leak. That improved the idle, but it still has a charging problem. This likely played into the dying problem. It seems to have more than one issue going on. Thanks.

[jase386]

check the fuel pressure regulator. friend had one that kept dying like that. took 5 mechanics to finally decide it was the fuel pressure regulator, once that was replaced, no more problems.

had two places tell him it was the alternator. one of them even wrecked his car while they had it, what a shame, but they repaired it, and still never found that the fuel pressure regulator is what was keeping it from running

[Smith1000]

Thanks. I will check the fuel pressure regulator. I am going to check the fuel pressure again and try to monitor the pressure while getting the car to do the problem. I tend to think it is electrical related at the moment, but will check the fuel pressure again.

I can get it to do it when sitting in the driveway by shifting it from drive to park. Right after getting it in park, there is a clicking noise and then the idle (sometimes, but not always) reduces very low and then the lights will dim slightly and the alternator will read lower (less than 13 volts). It does this for only about 2 to 3 seconds and then recovers and reads/charges normally. It won't do this every time I shift from Drive to park at idle-only about every 3rd or 4th time.

When it idles low, it does not idle rough. It is a very smooth idle, just low. When driving it, I let up on the accelerator when cresting a hill, as the engine slows, the idle will decrease normally and then "dip" lower (too low) intermittantly, causing the lights to dim and the elctrical cuts out not even for a second. It recovers and then runs and charges normally.

The engine never stumbles or backfires. The idle is very smooth. When it dies, you can see the tach needle "dip" quickly (foot off the gas). If it dips low enough, it will die. It has almost died many times, but has recovered. It doesn't do this on every hill or every time I take my foot off the gas. It is interimittant. It does seem to do it more frequently when the engine is under load (lights on, radio on, air blower on full blast).

There have been no codes related to the problem. I did have a code that said misfire, plug 6, right after replacing the cam and crank sensors. Is there a switch that engages/disengages when shifting from Drive to Park? I wonder if the neutral safety switch could be involved somehow. Here are the things I will check next:

fuel pressure/fuel pressure regulator

fuel pump relay, relays and other fuses

fuel pump wiring--ground wire, etc.

throttle position sensor--maybe causing low idle? Dead spot?

idle air control valve--possibly malfunctioning--controls curb idle

The fuel pressure regulator and idle air control valve are listed as common problems for the 97 Lesabre.

[spinne1]

Look at your list of things you're going to check. Step back and look again. Let it soak in. Think about the time you will spend. Think about the effort spent so far.

After all that I think you need to take your car to a good Buick dealer and let them diagnose it. Then decline the repair and fix it for good (hopefully). It will cost you under $100 but save you hours of frustration. How valuable is your time? Some problems can't be easily licked without the proper diagnostic equipment, which very few weekend warriors have.

[Smith1000]

Thanks. I understand what you mean. Fortunately, we have spare transportation and this is not real pressing to repair. I would like to get it fixed though. I have lots of time in the evening now that it is getting dark at 5:20.

I'll test a few items in the evening and few over the weekend and see what I can figure out.

[jase386]

cant wait to hear what you find. You sure have more time and patience than i do. i always buy parts and think im going to do the repairs and never have time to do them. then end up paying the mechanic to install my parts!!

[Smith1000]

I checked the IAC terminal resistance and it is fine. The reading is 59 which is in the range of 40 to 80. I noticed last night when checking some wires that the small ground cable from the battery negative terminal to the fender was very warm. Tonight, I'll check the large battery ground cable where it meets the block. It may just be a ground problem. The small wire may be carrying the ground load at times causing the charging drop. The battery terminals are good and clean as well as the smaller ground wires, but I did not previously check and clean where the large ground meets the block.

It hasn't died on me the last 3 times I have test driven it. Once the charge is going good, it will run great now. If I let it sit in the driveway at idle, full load on the battery, the battery juice eventually decreases and then, eventually, when shifting from D to Park, it will further drop the voltage to less than 12 volts momentarily and the lights will dim. The charging and rpms will them recover. It has not died when doing this; it just causes a decrease in voltage which reduces the idle slightly.

[Mickey#1]

Good find on the small ground wire, it certainly shouldn't be getting warm. I believe the large ground wire connects underneath the ICM mounting bracket. Look that cable over carefully, it's possible for the wire to corrode internally.

Fuel leaking through the diaphragm of the fuel pressure regulator could cause stalling at low RPMs. Pull the vacuum line off the fuel pressure regulator and look & smell for gasoline.

[Smith1000]

I pulled the vaccum line of the fuel pressure regulator and no gas or smell of gas. It seems to have a good vacuum there.

I added a ground cable this morning. I just ran a new one from the battery top neg post to near the ac bracket. My wife drove it yesterday and it ran fine she said. It hasn't actually died for quite some time, so I believe I will see how it goes for a week or so. She is running errands in it right now.

[Smith1000]

It has been running good and did not die at all yesterday. I still notice thought that when, for instance, you back up and put it in drive, that "switching" (it sounds like an elecrical switch--it clicks and the idle changes) or change in idle or momentarily increase in load, drops the tach and volts just for an instance (sometimes, but not every time). Foot on the gas it recovers fine and goes. It is not dying now, probably because of tightening the throttle body nuts. I am not exactly sure where the clicking or switch noise comes from under the hood. I think it is part of the transmission link. There are 2 electrical connections there. Someone may know what happens in that process.

It seemed to have 2 or 3 things going on. I am still not totally sure that the issue is resolved. I might look at some of the fuses and relays today. The switching or clicking after shifting to drive or nuetral, that results in the click and then idle change may be involved, however, it is running good enough now that it is not dying. It proceeds to charge well and I have not seen the tach "dip" or drop when driving for quite some time. As long as the dying issue is resolved, we should be okay.

[Smith1000]

It still has not died for quite some time, but it did register a code today when the tach "dipped". It had a P0122. This indicates " TPS/Pedal positon sensor A circuit low input".

Does anyone know this code. Maybe it is a bad throttle position sensor?

[Smith1000]

Here is an update:
It has died a few times since I last posted. I have 2 '97 Lesabres, so I swapped out some parts to see if it would fix the problem. I swapped the ECU, ignition modules and coils, throttle pos. sensors and Idle Air control valve. This did not solve the problem. It still wants to do the same thing. I checked all of the relays by swapping them around. It still has the same problem. I pulled the fuses on the right side near the glove box. They look good. I put them back in.

I checked the fuel pressure again. It is steady at about 41 lbs. at idle. When accelerating, it increases normally. The fuel pump seems to maintain fairly good pressure. It may go as low as 40 lbs occasionally and possibly to 39 lbs at times, but when it drops to low idle and low volts, the fuel pressure looks good.

I may swap out the batteries just to make sure it is not a problem within the battery. Right after shifting to park, the lights will dim, tach will drop and then volts will drop. It usually doesn't die when not moving. It will then recover and the volts will increase.

I disconnected the EGR valve wiring and it seemed to solve the problem temporarily....but, then it returned once idling for awhile. I may run it for a few days with the wire disconnected. I checked for codes and have no codes or a check engine light. Since I disconnected the EGR valve, there is now a check engine light.

I am still looking for ideas. The main issue is the idle dropping out intermittantly. When it drops the lights flicker and and proceed to dim and the charging decreases temporarily to below 12 volts.

[Smith1000]

I have discovered the idle drop has more to do with with pressing and releasing the brake pedal than shifting it into park. I had my wife press and release the brake. There was kind of a wheezing noise coming from out of the power booster. I believe it must be leaking air or losing vaccum internally. When the pedal is pressed or released, the idle hunts. It initially will drop very low after releasing the brake pedal. The vacuum loss is resulting in the low idle. The slow idle translates into a drop in voltage.