moon928

Good morning,

I need help. My 88 S4 with 104k on the clock will not turn over. Two weeks ago the car suddenly went into limp mode while I was on the highway and I just made it home. I suspected the MAF but after reading several posts on limp mode and MAF failure, I tested my MAF, I can safely say that is not the problem. I could get the car to turn over while testing the to see if it was the MAF no it wont start at all.

I visually checked the coils and the wire at the caps to see if they were loose or grounding out. They were not. I thought something may have got wet since I had driven the car in some heavy rain the day before she went into Limp mode, so I let her sit for two weeks to dry out. I tried cranking her over today and it is struggling to turn at all. I am at a loss.

Any help would be appreciated.

Thanks,
‘Moon’

dr bob

Two weeks not running for some cars is a long time. Start off by pulling the ground connection at the rear apron and charging the battery. Once that's done, reattach the ground strap and do a little diagnosis.

Brain faulure is very often associated with some symptoms. Biggest is that the injectors will chatter with the key on but the engine not started or cranked. Hood up, key on, listen for the noise under the hood. Don't do this for long, though.

You might mistake "running on four cylinders" with "limp home mode". If you have an ignition failuire on one distributor, two cylinders on each side of the motor will not fire, and the car will be weak on performance. This is a very dangerous situation since those injectors will still be dumping raw fuel into the cylinders. That gets pumped to the catalysts and is a too-common cause of fires under the car as the cats overheat.

Staret with the abttery charge so you can crank the car, and diagnose from there.

Also, if there is water in the caps you'll lose one or both side ignition. Mark the wire locations, and pull the caps and dry them out. Screwdriver and/or nutdriver to get the caps off. You can probably get them out enough to dry them if you just pull the coil wire and the one tight ignition wire off of each cap before rotating it up to inspect/clean. A little brake cleaner on a rag will do a good job of cleaning and dryiong the inside of the cap. Clean the rotor too. Reassemble after the fumes have dissipated and try again.

Let us know how you do with this.

moon928

Thanks Bob. I will start with basics and move forward. I wasnt sure how old the wires were so I checked the records the PO gave me when I purchased the car, and the wires were replaced in 2001 with a set of Nology wires, the caps and rotors were replaced in 2002. That was about 30k ago which seems fairly new to me but as you can tell I am a beginer at this. How long should they last?

I will let you know how I make out. Thanks again.

Rich9928p

Dr. Bob gave sage advice - I'll go a little further. The majority of no-start problems are electrical related, and it makes the most sense (to spend the fewest dollars) to go after the most common and least expensive items. Start with cleaning connections (ground and others), and check relays. For S4s the horn relay fits the LH, EZK and fuel pump relay sockets - a toot on the horn proves that relay is good and it can be plugged in the others - one at a time - to see if they're the cause of your no-start condition. If these suggestions don't help, let us know and we'll go the next level down.

worf928

Jim, if you've procured your CD-ROM shop manuals there is an LH diagnostic matrix and guide thereto which, if you have a multi-meter, you can use to troubleshoot 80% of the possible culprits.

MBMB

Moon,

"Struggling to turn at all" doesn't sound like a fuel problem or an air problem or a spark problem to me. If any of these things were the problem, I would expect the engine to turn over briskly at first, then slow. Are you certain that the battery is in good working condition and charged? You might pull it and take it to an auto parts store where they can load-test it.

If the battery is in good shape and charged and the car struggles to turn over, I would check the major ground points and the starter connections. If those are all clean and tight, I would suspect the starter (though this is not a mode of starter failure with which I'm familiar).

If it's not the battery, the connections, or the starter I fear some major problem -- something spun or seized in the engine. Were there any ugly noises when you last drove her? Pull your dipstick, take it away from the car, and sniff for gasoline. Gas in the oil suggests that you weren't getting spark in some cylinders when you last drove her; unburned gas in the cylinders has been known to wash the oil out of the cylinder bore, causing unpleasant unlubricated intercourse between the rings and the cylinder.

moon928

I didnt hear anything loud or out of the ordinary at all. It just lost power. I actually thought the car shut off.

Worf- I have my Work Shop Manuals - now but I am pretty clueless when it comes to all of this, but I am willing to learn.

I did check the oil this morning and I fear you may be right Mark- I did detect some gas in the oil.

Jim

Jim bailey - 928 International

Moon.."I tried cranking her over today and it is struggling to turn at all. I am at a loss." Assuming that the battery is fully charged this bit of information would have me wondering about the thrust bearing. It is an automatic ! It might be worthwhile to remove the sparkplugs and see how it turnsover on the starter.

dr bob

This is an ugly thought, but very possible based on the symptoms. As Jim suggests, pull the spark plugs. If you are going to spin it with the starter, pull the EZK relay too so you don't trash the coils. Otherwise, turn it over with a rattchet and socket in the front crank pulley (27mm or 1 1/16" if I remember correctly...) and see if it's really hard to turn or just a bit hard.

The failure Jim refers to has to do with some twisting/shortening issues with the driveshaft. Under some high-load circumstances, the driveshaft will twist and shorten enough to pull out of the flex plate a little. When the torque is reduced and the driveshaft returns to normal length again, the flex plate is not in the right position any more. It has moved forward on the shaft, and with the shaft at full length again, it will push the crankshaft forward against the thrust bearing surface that's part of one of the main bearings. In extreme cases, the pressure against that thrust bearing is great enough to wear to the point that the crank grinds against the block, and the engine will be hard to turn over. Not much hope for the motor if it gets to that point, so say a prayer and take a look.

The definitive test uses a dial indicator to measure crankshaft endplay. Before doing that, you'll need to release all pressure from the shaft through the flexplate. That requires that you lower the front of the exhaust from the header flanges, remove the cover on the bottom of the bellhousing, loosen the socket capscrew on the clamp that holds the flexplate to the driveshaft. Watch to see how much the clampo moves on the shaft-- This is an indicator of how much load was being transferred to the crank.

There are undoubtedly some owners near you who can help you identify this problem if your local mechanic isn't aware of the issue. There are more than a few threads in the Rennlist archives too. Search for "TBF" and "Thrust Bearing Failure" and go from there.

Keep us updated on what you find.

worf928

Please correct me if I'm wrong Dr Bob, but doesn't TBF usually manifest itself as no-start on warm condition rather than a no-start on cold condition? (Just trying to save Moony from a trip to the cardiologist here...)

Jim, sending you a PM.

Rich9928p

It all depends how bad the failure is. There would be quite some racket if the crankshaft counter weights were banking into the bottom of the engine. The starter motor could also be going bad - it doesn't always have to be TBF!

Jim bailey - 928 International

Rich the grinding away of the shoulder of the thrust bearing followed by machining of the webbing makes little or no noise at all. Thrust bearing failure in the later stages can cause so much drag that the engine stalls. In the initial stages it is not uncommon for the engine to turn over and start after a lengthy cool down period so people chase a "hot start problem" but often continue to drive the car since it starts and runs fine cold. His comment that it lost power that he barely made it home now that it barely cranks could be consistent with extreme trust bearing failure. As always long distance auto diagnosis is but a GUESS and is based on comments observations which are not always clear. Even the term "turn over" to some seems to mean fire and run ! Personally I tend to want to eliminate a potential dead engine before spending a lot of time and or money chasing down other possibilities. Something I learned after watching a good mechanic work for hours trying to adjust the two carbs on a 356 only to discover it had a dead hole low compression on one cylinder! (the customer did his own tune-up and brought it in JUST for a carb syncronization)

Gretch

Moon, I am local to the Boston - Westborough corridor. I can come and look at the car if you want....First, I suggest you pull the oil filter and cut it in half, if you can change the oil where the car sits, I would do that too. you are checking for metal filings....if you don't find any you will sleep substantially better while you look for the no start cause....

Jim bailey - 928 International

Gretch very nice of you to offer to help check things out ..I was not 100% sure it was a no crank situation or a no start ... if you bring a "spare" LH Brain and mass airflow sensor and compression tester (confirms cam timing) much could be accomplished. And as always relay, relay, relay....

heinrich

Driving a 928 in heavy rain, especially with no bellypans, can get the alternator wet, especially if the cowl and tube aren't secure (ha! how often is that tube OK?) ... so, I think your battery is kaput.