: 85 4100

01-03-10, 09:58 AM
Got a new problem, the old girl has run like new until a month ago. The code states 38 (open map sensor circut) put new ones in but still got light and code even ater reset. car starts and runs good but while driving i you push the gas it'll start to choke out and you have to ease of gas. any help here?

01-04-10, 02:37 AM
I believe 38 will also set when there is no or low vacuum to the MAP. Check/replace the vacuum line running to the MAP sensor to rule out any vacuum leaks

01-10-10, 10:03 AM
Well I checked and replace all the hoses so I know there is no leaks, still getting the service soon light. I am wondering if the fuel pump has a lot to do with my problem? As I said, it runs good til you get around 40 and if you push the gas she'll start coughing. But if you push down to the floor on her she'll take off without the coughing. At first I thought if was the carb, but I have change the carb 3x's now and still have the same problem. She has a bit of exhust leak going on, I am wondering if she's got a burnt valve?

01-10-10, 10:19 PM
My guess is gonna be EGR. One of my cars was having the same symptoms(stumble on slight throttle take offs, stumble at 45-60 with light throttle) and a vacuum code would pop up. Another symptom of EGR is bad gas mileage. Went to the junkyard and grabed a couple, one worked great and now the problem is fixed. Smooth sailing at all speeds. If all hoses are now new, might as well grab a different EGR. They were three bucks each at upullrparts. You can test it with a vacuum gauge also.

01-11-10, 06:31 AM
Thanks! I will be stopping off at pull-a-parts and see if I can find a few and give that a try. anything to get the old girl running smooth again. Also, come to think about it, you amy be right because when you push the EGR in the car will choke up a bit and that is just how she is acting. Many thanks!!!

01-16-10, 03:07 PM
Well, new EGR and new MAP sensor(s) since there are two on this bird. and still getting code 38 with "service soon" light. I have replaced EVERY hose on the old girl but still no fix. I am thinking about doing a new fuel pump, the cad converter is new so I can rule that out. Any thing anyone can offer here?
Thanks, Dave

01-16-10, 11:45 PM
What amount of vacuum is coming thru this new MAP hose? If the source vacuum is restricted then you'll get this code and a performance problem as well. I would look at the opposite end of this hose where it attaches and verify strong vacuum is present. Over the years this vacuum port could have carboned up making the port smaller.

01-18-10, 04:04 PM
agree to check vacuum. could also be m/c solenoid in carb.

01-18-10, 07:32 PM
when you push the EGR in the car will choke up a bit

That means the EGR is fine.

01-19-10, 06:06 AM
This bird is driving me nuts. The carb and all the parts are new. I falied to state that I am wondering if the computer could be bad? The cars computer will come on while driving, she spit and choke a little when I puch the gas and then once in a while the computer kicks the heater off and starts showing the code (38). My brother told me once that his wifes car acted up then found out it was the computer causing the whole problems. I am going today to getting a new one and give that a try. If that don't work I guess I'll have to take her down and just rebuild the whole engine, but I got to get my N* HG's done first.

01-19-10, 09:30 AM
these computers dont usually go bad. The car goes into safe mode once certain codes are set, I beleive the timing changes by 5 degrees to keep the heat down(someone correct me if Im wrong). When I get home, Ill check to see what the service manual says about code 38. Any signs of bad timing like hard starts when warm, bad mileage or deiseling? How does it do around 45-55? plugs and wires?

01-20-10, 05:35 PM
Nope, the car starts like always, great. She runs rough a little, and turn off right away with no problems. If I get up to 40 to 55 she'll choke up a bit if I push the gas and then the computer will kick on while driving. Code 38 is an open map sensor curcit. I have a exhust manifold leak and I am wondering if that could have caused a burnt valve? The car has ran like new for the past 25 years, this is the first time she has acted up.

01-20-10, 08:09 PM
so the book doesnt go too much into this code but it does say that a throttle position greater than 21% and rpm over 1200rpm will set the code...or the vacuum signal is too low under 1200rpm. It also says that if the computer recognizes the high map signal, the computer and wiring are good. It doesnt go far into it without a scan tool but I would say that you have low vacuum at lower rpms for some reason. Maybe a throttle position sensor or idle air control sensor causing low rpm and tripping the code. Your at pretty low rpms around 40-55 also. But a bad spark will cause very simular problems also.

01-03-11, 05:36 PM
well I got the last problem fixed, it turned out to be the cad convert!! Put new one on and light went out and runs great!

01-03-11, 05:46 PM
now I have a new problem, it seems Janurary is her month for problems. I can't get the battery to charges. New alternator (changed 3 times to make sure) new battery ( also had it checked) and new starter. 300 dollars later and still getting a low voltage. replaced wire going from battery to alternator, no fix. Anyone got a clue as to what I can do and what else I need to check?

01-03-11, 06:09 PM
When I saw the date on this (1.03.1X) in the thread listing, I tried to remember when, today, I left a reply... Then I realized that I didn't reply until tomorrow. But today is yesterday and tomorrow was today, so maybe I did leave that reply sometime this morning.

01-03-11, 06:11 PM
Test the alternator output with a multi-meter; it's either charging to spec or it's not.

01-05-11, 09:16 AM
If this car is a rear wheel drive Fleetwood with a 4100 FUEL INJECTED engine then the most likely reason is a loose smog pump belt. If loose, then the alternator will slip and provide low voltage. If you can rotate the alternator pulley by hand against normal rotation ( engine off ) then the smog pump belt is loose, not the alt. belt. This belt is tightened from under the car and is rather a PITA to get too. If its been slipping for awhile, the belt is now glazed and needs replaced. I just re read this thread from the beginning and you refer to replacing the carb?? A 4100 never had one?

01-05-11, 01:32 PM
And why did you use a year old thread to post this new problem? Most will ignore it because of the original date posted.

01-09-11, 06:21 AM
Well I call it a carb because it still is a carb only has 2 overhead injectors. But I am still getting the low voltage from the alternator, this is the 4th one how (exchanged it 4x) replaced the wiring cables from alt to battery and still luck. I have cleaned all the grounds I can find and still no luck. Battery is new (2 weeks old). Had the battery checked and it is good. This all started when I replaced the starter. 1st starter had open ground because the battery would go down sitting for more than 2 days, so exchanged it for another. Now no more problems with battery going down but now the I am getting the low voltage from the alt and the car will start draining the battery while driving. When the battery is charged fully and running I can take the neg cable off and the car will run, but reconnect the cable and drive the car it will start draining the battery. Anyone got some other ideals as to where I should look? Thanks!!

01-09-11, 10:51 AM
Removing a battery cable while a computer controlled engine is running can damage the computer itself. I guess you can lead a horse to water, but ..... I say again, is the smog pump belt loose? yes or no?

01-13-11, 05:07 PM
First of all this is a 4100 engine with 5 belts, the smog pump has its own belt and it is not lose. The alternator has its own belt and it is not lose. Like I said before, this all started when I replaced the starter. 1st starter went out, so I got another (lifetime starter) the second one had open ground and would drain the battery if dat more than two days so exchanged it again and no more draining. But the alternator reads low voltage and I have exchanged it 4X. Could this starter be bad and be causing the low voltage reading?

01-13-11, 05:32 PM
Throwing parts at the issue is never the answer. Once the second alternator/starter failed to fix the problem, you should have realized that it may not be a component malfunction, which is causing the battery to drain.

Does the "NO CHARGE" Lamp come on at bulb check? If not, then replace the bulb. The charge circuit is routed directly through the bulb, and if the bulb is blown, the battery will not charge fully.

Did you check the condition of the other wire going to the alternator? Did you check the condition of the connector to the alternator? Both of those, if damaged, will cause inadequate charging of the battery.

01-14-11, 02:15 AM
I agree regarding the battery red light in the dash. Not lighting up can lower the alternator output. Does it light up when the key is turned to the on position? then go out when the car starts. Can you rotate the alt pulley by hand in its opposite direction, yes or no? If no then I agree, all belts are tight enough. You say low voltage. Please post the readings. With the car off what voltage reading do you get across the battery posts? With it running what voltage reading do you get across the battery posts? What voltage reading do you get at say 1500 RPM? across these same posts.

01-30-11, 07:31 AM
OK, dash light is good, new battery, new alt, and replaced wire from alt to battery. Still low voltage only on the car, when off eveything is reading ok. I am getting a reading at battery post of 11.49 with car off, and running it only starts to drop. I had to replace the starter, then had to replace that one due to having an open ground (if car sat for 2 days it would drain the battery). All my problems started when I replaced the starter, I am thinking that this starter maybe causing the low voltage due to be pulling while the car is running. I live in Elyria, Ohio and it is very cold and the car is not in the garage due to extra items my mother keeps LOL, so does anyone thing this might be the problem too? I really want to my old girl going, I am a bit older and can't take the hard ride my grand prix has (which I am selling once the caddy is fixed).
Many THANKS to all who is helping me.

01-30-11, 03:34 PM
Maybe there is another bulb for no charge? One for battery and one for low charge? There can't be much to a charging circuit, maybe the small wire going to the alt is melted somewhere or the fuse to the computer is blown.

02-14-11, 05:56 AM
Well guys, my SINCERE APOLOGIES to carnut. When I'm wrong I'm wrong. The smog pump belt broke about a year ago, I was down with a back surgery and had to have someone else to the work for me (thats what I get when I let others touch my cars) but yesterday I was working on her and all the belts were tight, then the smog belt broke and I went to AZ and got a new one. Looking at the new and the old one I found the other guy put the wrong belt on my car. Once I got the PITA new one on all the power came back and no problems with the charging. Thanks to everyone who has helped.

02-15-11, 10:37 AM
You're welcome. Could you share the part number for the correct belt to help others?

02-16-11, 10:28 AM
You sure do a lot of parts changing there!

I see it was a belt which was a big suspicion of mine.

Some of the other posters are correct when they state that continuing to change the same part is usually not going to solve the problem.

You may want to get an old school multi meter that can read amps as well as volts. that'll come in handy in the future.