Ok I have an 88 na with a manual tranny I just picked up, and it came with a few questions.

#1 When I cold start my car it revs up to 3000 for a sec (which I know is normal) then drops to 1500 (which is also normal) but it doesn't stay right 1500, the RPM's fluctuate by about 200-300 while it's warming up. Is this a normal function of the cold start system?

#2 I have a warm start issue. When the motor is warmed up, if I shut it off and wait a few minutes (say like when I go to the store) it takes a little for it to start up, and it idles lower, sometimes stalling itself out. I followed the FSM method of properly adjusting the idle, but no matter how far I adjusted the idle screw my RPM's would not increase (screwing it in did lower my RPM's though.)

#3 One time the car died while I was driving, lights started dimming and eventually it quit. I had the alternator tested and they said it was ok. I put a new battery in it and replaced the alt belt. Since doing all this the car hasn't died on me yet, but I have noticed that sometimes the voltage gauge drops to 12v, regardless of the engine RPM's. I really don't want to get stuck again (who does right?) so I'm looking for advice on things to check out.

PS. When I put the new battery in I replaced the ground cable from the batt to the chassis (ground to the starter was not removed), and I also replaced the ground between the chassis and the engine. I have not touched the ECU ground yet.

 

1) TPS is out of adjustment or has a small dead spot.

2) Common hot start issues. Give it some throttle to let it clear the excess fuel. You can also adjust the idle speed higher via the throttle stop screw. A little bit goes a long way.

3) In almost all cases, the alternator is to blame for charging problems. The stock S4 alternator is also pretty weak, so if you have any aftermarket add-ons that will draw power, the alt. will have trouble keeping up. Was the alternator load tested, or did someone with a multimeter call it ok?

 

1. I'll check out the TPS this weekend when I got some free time.

2. I'll go to the FSM to find said screw. Should I use this to increase my idle, then hook the tach and jumper back up and fine tune the idle with the screw on top?

3. I took it to my FLAPS, they bench tested it, said it was g2g, but we all make mistakes. At the time that the car died, I was only running headlights and my brakes (was coming to a stop) the stereo and etc was off.

Thanks for your help, added to my todo list for the weekend.

 

Small update. I was driving home from school today and the voltage gauge was reading 12v from the second I started the car. Since I pass my FLAPS on the drive home I decided to stop in and have them bench my alternator again. They tested it, and again I was told it was g2g.

The real fun part starts while I was reinstalling the alternator. While tightening down the positive lead, the bolt coming out of the alt snapped. Now I was not so stupid as to wrench that bolt down, maybe I crossed threaded it, but that's no big deal. I'll use this as an excuse to upgrade to a bigger alt now. My girl is gunna love to here that lol

 

A lot of people put on FD alts.

 

I didn't want to bother with the alt swap until I was ready to re-do the stereo. Didn't want to buy an alt until I knew for sure it was the problem. Looks like what I want doesn't really matter lol.

 

I had a similar issue with the warm start issue, my problem was with my Fuel Pressure Regulator. Once i replaced it, i had no more issues starting. You can check that out.

 

cool man, ty for the info

 

Just did the FD alt swap, was pretty easy and now my voltage is rock solid at 14.4 (regardless of what accessories I'm running.) I'd like to to thank everyone on this site, as it was a great source for information. I also found out something "neat". My water temp sensor that is mounted under the alt was completely broken, so that something new to add to the parts list.

Also, a buddy of mine who use to own an 87 s4 came by and dropped this off to me...





One exhaust gasket away from slapping this bitch on!

 

beware will be loud...and u wont pass smog

 

Thankfully there is no smog check in my part of Oregon. We're here to cut down trees, not save them. And my buddy did say it was loud, I might chop off the mufflers he was running and go with something a bit more adult. He did throw in the 45degree dump out that goes right on the presilencer though, I'll definitely have to put in on for just 1 day to try hear it.

 

thats a nice exhaust

i just dont really like the tips, did you put it on yet?

 

Yeah i got it all slapped in, and it is a bit loud. If i had more sound dampening in/around the spare tire well it would probably be bearable inside. Outside it is still a cop magnet. Been looking at getting a pair of those slip in exhaust baffles to tune it down a notch.

I also had to tweak the mounts on the presilencer a bit too. it would drag over speed bumps, and the car is not even lowered. Got that all sorted now.