sleuths might get a challenge on this questions fuel or tccs

This seems odd to me so dig in if you like a challenge to prove your skill. Or maybe this is easy and i am stupid.

current issue then background' 1998 Lesabre. Suddenly with no previous issues and about 120,000 miles I think, while on the freeway doing 75 it jerked, or hesitated?. It was similar to back off throttle and back on again. There was the heavy sound that comes with it. Sorry for the poor description, I am a bit better with cars than my vocab shows. My first thought was fuel issue. I am out of state and thoughts and dred are racing through my mind. no idiot lights are on. keeps surging with some drop in mph but usualy will pretty well keep speed if I try. I back off gas and coast cut the a/c and try to accel, same symptoms. I jus bought gas aobut 40 miles ago, was it bad or different? I wonder, and adjustments are being made for it, or the altitude? Is it the tranny? I did not know.

Big story; This first happened a bout 2 years ago in close to the same spot. (to jump ahead a little, when I returned home it did not do it again) I live in eastern washington elevatin about 150. I was in Idaho just got gas each time and was in higher altitude and climbing. I thought altitude might be a culprit. Well this trip ends in Vegas. eventualy I slow down to about 20 try to hold that speed and it does, so I accel and it is normal, for a while. So both trips this issue starts in Idaho (it may have happened 3 times or trips I dont remember) This time it lasted longer and more times , but it usualy quickly goes away either I slow down or stop or stop and turn off the car and the problem goes away.

Once in vegas it occured a couple of times. Still wondering about elevation cause vegas is higher than home. Realized fuel at home also has 10 percent ethanol. Thinking the inhjectors could be dirty but would not expect that to just go away and then come back. Not sure what alll the feeling of tranny trouble is but did not think it was slipping, kept thinking about the torque converter clutch control solenoid. I had that problem in my 89 century some yeats back. After a 8 days in vegas the problem occured on the way out of town actualy about 20 miles out and once or twice before or maybe just inside Utah. then no trouble. I am planning to replace tranny fluid and filter but have not had any sign of the problem and all the while between these trips there have been no issues. I have crossed mountain passes but not as high as this trip. some months ago I had started to wonder why the car is getting about 5 miles to the gallon less on the freeway. Other than the mpg drop there is no signs of any issues. I changed the fuel filter and checked the plugs that i think were replaced about 2 years ago along with wires. The mpg might be connected I dont know, cause I dont know what is going on yet. Since the symptoms dont occure or have not occured here other than on those trips, (maybe once real quick but too quick to say, while at home last year) It idles fine during these episodes.

So sleuths what do you think is going on? If it is the tccc solenoid why only on those trips?

Without onsite testing to feel the condition anything we throw out is guess work, low fuel pressure, poor connections to the icm or crank sensor, failing icm, intermittent, failing crank sensor, failing ign switch all can give similar symptoms to what you describe. Major altitude corrections are done though the map sensor and maf strategy to alter fuel and timing curves and yes a skewed maf is also in the mix.

Thanks for the reply. Yes I had been meaning to replace the sensors.

I know sometimes thnkgs take a long time to fail completly and it can be strange. But given the length of time, 2 years, and the lack of symptoms other than on these trips and especialy the length of time this has gone on. Doesnt that make you thnk some of those possiblities could still be likely but just not probable? Or not?

you did not mention clutch solenoid. Is there something in there that makes you doubt it is a culprit?

I still want to blame altitude, but I have been at least 1500 feet several times. wouldnt you think that change would be enough to trigger an issue?

Also if I change the sensors is there a way to test without driving to idaho,? lol.

bad gas is my guess.
When you get bad gas it will depend on how much good gas you had before
filling.

Cheers
Stripe

I would avoid just throwing parts at this without a full inspection and scan first.

updadate. all this time at home we again have not had the problem duplicated as on the trip. I am back to my first suspicion but for some reason felt it wrong. It must be the gas. i know some states have diff. requirements. So would heet work? I assume it is water. So some form of gas dryer is needed? If not water but still a gas issue what?

Sir,

Most gas these days has some alcohol in it (gov't likes it), so that tends to take care of the water.

We did have a problem with our '97 some time ago; it ran very poorly on a trip, but it did run to a service station. I assumed a bad fuel filter and had them change it. Then it ran well for some time. Later it just quit on a hot day! We were left hanging, the hood was up. I tried to restart it and it did get us home. Turned out to be a bad crank position sensor. Maybe it was misbehaving earlier when I thought it was the fuel filter.

My '91 had a similar quitting-then-restarting-after-cooling behavior, so the crank sensor was changed right away. SO-----maybe you have a failing crank position sensor???

Regards,
Jack C.

Ihave a 92 3800 it had a crank sencor go bad but they just give the huicup you talking about till they go bad and have the intermitten no start so i lean to maxwedge as to the map sensor because it happenns at higher alt and it is one of the less costly parts to replacebut a live data look and a check on fuel pressure would not hurt

Someone correct me if I'm wrong. I believe the the MAP sensor can only check the ambient pressure at start-up before the engine actually starts. If your climbing a mountain maybe you should stop half way & turn the key to run for a second before restarting.

Actually, the MAP sensor constantly monitors manifold pressure/vacuum and sends varying voltage to the PCM based on engine load. The PCM uses this information to adjust engine timing as required. Before replacing a MAP sensor, it is best to look at voltage output on a scanner, to see if voltage varies while under load. As Max mentioned in AUGUST of last year; "I would avoid just throwing parts at this without a full inspection and scan first."

I am pretty cerain at this point it is fuel. I will be going through there again and will use some sort of dryer.