98 Seville electrical problem and stalling

Transman

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Wow, Thanks for the donation. We all appreciate it. I agree with Joe about the crank sensor but don't forget to pull the connector from the range switch and look inside.
Thanks Joe for the insight to onboards for the sts. I always liked onboard for caddy diagnostics and according to shopkey they simply aren't there on that model. I can't wait to try it out on my next one in the shop. Transman
 

jjksak

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Thanks again.
The only code I am getting is "Engine stall or near stall", which the manual tells me is set when the RPM's fall below 450. I will check the items you listed. The factory manual gives a checklist for this code, which pretty much covers the air, fuel, and spark systems. I pulled the air box/air intake looking for any restrictions and didn't find any. Some past owner installed a K&N filter in the air box and I cleaned/oiled it with K&N kit. A friend of mine has a ram intake that will fit this car, including adapter for the MAF sensor. Will this increase the air flow and maybe stop some of the stalling, or will it upset the computer?
I'm going to change the fuel filter, as I don't know when it was last changed. Thanks.

john
 

Transman

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Sorry, but I wouldn't doubt the air filter is the cause. Overoiling is the biggest problem as the oil comes off the filter and lands on the MAF causing it to read the air incorrectly as well as causing it to fail prematurely. Get a good MAF cleaner, not carb cleaner and take that k&n, run over it a few times and put the factory air filter back in. If the engine problem improves then save up your money for a new MAF because you are probably going to be needing a new one soon. Transman
 

jjm

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Transman, no problem, glad to help! But I can't believe I was actually able to help one the "masters" here.

The ON/OFF and UP ARROW trick should work on the STS/SLS up until 2004 - apparently starting as early as the 1998 (thought it was only the 1999 and on) - and on the DeVille/DHS/DTS from 2000-2005... I make PLENTY of use of it unfortunately... even while driving (sigh). But the party seems to have ended - on the MANY MANY 2006-2007 rentals I've been stuck in while my 2005 DTS was in for something or another, I couldn't find a way to get into self-diagnostics. Doesn't mean they no longer have them, but I sure as heck couldn't seem to find a way to get in.

Need your opinion... mine's going back AGAIN for an ongoing nav problem (finally making some progress though; OnStar VCIM/VIU was pulled and amazingly the nav isn't screwing up anymore), and I think there's a problem with the 4T80E. Seems the 2-3 shift has gotten "sloppy" perhaps even slipping slightly with a bit of bump afterwards... hard to tell on these high-revving Northstars. Doesn't do it all the time, and it seemed to act-up after the last cold snap. Is this a sign the 40T80E is getting ready to bite the dust? It always shifted a little to rough on the 1-2 when cold, but now the 2-3 gets sloppy on moderate acceleration when warm. The only reason I'm asking is with nearly 44,000 on the clock, the factory warranty is fast running out.

Well at least I know a REALLY GOOD tranny guy if it goes outside of warranty!

I didn't mean to hijack the thread... sorry! Of all the motors a K&N air filter could go on, not that any of them are good candidates, but the Northstar has got to be THE WORST for one. I would seriously consider getting rid of it (I like target practice better than running over it though) and reinstalling the correct factory air intake. Northstars are pretty much engineered to perfection anyway... you're just not going to get much more out of that 4.6 unless we're talking turbos and superchargers. Not that I'm advocating that, don't think those engines could handle that kind of abuse over the long haul. These are mass produced all aluminum engines after all, and don't seem to handle driving by the largely 75 plus crowd all that well to begin with.

Forget the other mod, upsetting the computers - especially with a "different" MAF - will likely be an understatement.

By the way, you didn't mention the specific codes you got.

Joe
 

Transman

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Joe, The trans shouldn't be going but they did have a big problem with the pressure regulator solenoid (epc) as well as shift solenoids and the main harness inside. Don't forget the range switch (neutral switch) and this is the first place I would start. If you CAN get the connector off look for corrosion inside, the sealer GM uses turns into krazy glue after a bit and makes the connector next to impossible to get off. You may have to hook up a trans capable scanner to see what kind of pressures the epc is commanding and if there is any slip error. Check the fluid level and smell, if ok you might want to add a bottle of lubegard "red".
P.S> Glad I was able to inflate your ego, lol but trust me, I don't know everything. Just don't let my guys hear I said that (Grin). Transman
 

jjksak

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Intermittent stalling finally stopped for good after I removed and cleaned the injectors. (I performed the other suggested maintenance on car by posters. Thanks!)

I found the drainage on the battery was caused by the computer checking the CD player operation every minute or so, causing the CD player to run with car off, and drawing ~5 amps when this occurred. I fixed this by installing a 12 volt relay in series with the fuse for the CD changer, and wiring the coil into ignition wiring, so I only have power to CD when key is on. Only code I get now is telling me that the computer has lost communication with the cd player, which is a minor code. Battery voltage hasn't dropped below 12.4 volts ever since!

Thanks for telling me how to read the codes on the 98 Seville!! The 3 1000-page factory manuals wouldn't even tell me how to do it, and my scan tool was useless on the minor codes on this car.


Best $25.00 I ever spent online!

Thanks again!

~jjksak
 

Transman

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Thank you for posting your fix, We are very happy when people post what made their vehicle good again. It also helps us diagnose better. I am sure you are aware how difficult it can be to diagnose a vehicle when you can't see, hear, and run specific tests first hand. What method of injector cleaning did you do with this? Additive or motor vac style cleaning? Transman
 

jjm

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I'm curious about what method you used to clean the injectors too, but I'm glad the problem was corrected.

I'm also glad to hear you found the battery drain problem, but I'm not to thrilled at the solution. Yes, the solution does work, but the underlying problem has not been corrected. Whatever is bad is still bad. Ideally, you should've disconnected the radio to see if the radio was still energizing the CD, and if so, have the radio repaired. If the CD player was still engergized with the radio disconnected, then the either CD changer is bad, or something along the Class II network is holding commanding the radio on. Since there didn't seem to be any codes to this effect, my feeling is the CD player itself is bad, and should've been repaired.

Ok, I'm a little bit too anal... I admit it. Either way, we're glad we helped!

You like that little trick for pulling all the codes through the DIC without a Tech2 eh? You won't find that in any Cadillac manual as you discovered.

Joe
 
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