The Forgotten On

Alright everyone. My S4 is acting up terribly.Now for some backstory on the beginning of this issue.

I had the car die originally from a loose battery clamp which left me stranded because the relays started buzzing furiously.

I could not find the issue at the time after a 300+ mile drive home from Sharks in the Park when driving home from work same day and had the car towed home.

I found that issue a few days later and fixed it after having the LH tested and serviced by Rich Andrade.

Then found out the fuel pump relay socket was broken and replaced it with the Porsche part along with a new ground strap, again from Porsche, at the same time. Got the fuel pump working when jumping the pins in the LH computer connector.

Then it wouldn't start and the fuel pump wouldn't run so I replaced the cps (which was a FAE part) with a new Bosch unit.

Then finally tried to start it and after cranking it for ages it finally started with a lot of black smoke out of the exhaust, fumes that burn your eyes and stink up the neighborhood along with a rough idle that is hunting around rpms 800-1200.

It will rev fine but has trouble idling and will stall. I also shut the car down after a few minutes because the cats started to glow a bit on a few of the thinner sections.

I replaced all the hoses under the intake along with all the gaskets in a function over form intake refresh because the ISV hoses split. The car ran fine after this for months.

All the major sensors like the knock, cps, temp II, 02, and maf were all replace within the last 4 months with Bosch parts. The Maf coming from 928 International.

I also replaced both ignition final stages and all plugs, caps, and rotors from a separate issue a few months ago with 1 final stage intermittently failing. The plug wires are 8 years old.

I tested for vacuum leaks by spraying around the intake with brake cleaner (I know, not a good idea) but the idle didn't change behavior at all.

I also tested the FPR and FPDs and they don't leak gas into the vacuum lines and hold vacuum wonderfully. I also reset the LH by disconnecting the battery for 30 minutes with no change.

It is also worth noting the car does have PEMs installed, but they had hundreds of miles without issue on them when the problems started.

Anyone got any ideas?

jcorenman

Blake, this brings a whole new dimension to the usual advice of "check whatever you last changed"...
Was it tested or refurbished? Can you get your hands on a stock LH for a test?
Sounds like one ignition bank is off, or stupid-rich. I would bet on a bad coil. Are the coils black, or silver?
A few seconds is enough, but even a confused LH can't be more than 20% off for fueling, which I don't think is glowing-cats rich.
Do you have access to a Sharktuner? Check all the sensor readings (Temp II etc)
Check for spark on both banks, replace any silver coils with proper black ones from Mark. Check the ignition amps, if they aren't Bosch then back to 928 Int'l.

The Forgotten On

Everything was running fine until the battery terminal came loose and then it went nuts.

The LH was tested and had the capacitors replaced by Rich. It was replaced at some point as it was made in Spain. It ran fine in Rich's car as well.

The coils are original. But I know what running on 1/2 of the cylinders feels like with my final stage issues and this wasn't it. It didn't even smoke when half of the cylinders lost ignition. Nor did it have the long cranking issue it is now.

It also wouldn't rev with 1/2 of the ignition down and today the car would rev happily but couldn't idle to save its life.

Plus with an 89, the IMS will cut fuel to the bad bank. This thing is still running on all cylinders somehow.

I'll check fuel pressure next to see if the regulator failed with high pressure. You never know. This happened to Rich some time ago when I talked to him.

I think the MAF may have died again as disconnecting it had no difference to with it plugged in.

This all happened after a 300+ mile drive without a single hiccup.

FredR

Definitely not good- have you checked the wiring under the MAF connector weather boot recently?

The Forgotten On

Not personally, but the PO replaced the plug and re-wrapped it in self vulcanizing tape about 3 years ago along with changing all the connectors to the modern Bosch connectors you squeeze to remove (best upgrade ever).

The wiring itself is actually still very pliable and not in the least bit crispy on the LH harness. I personally think it was replaced at the same time as the computer because the sheathing is black and not the brownish grey I see on most other ones.

Even the grounds were clean on the engine and the main engine ground strap is still shiny copper so that should be fine.

I think I'm going to send it to Rich in AZ to see if it is truly knackered after I ohm out the wiring from the ecu connector in the car to check for shorts.

The Forgotten On

I also forgot to mention I didn't reset the computer with the maf disconnected. I'll try it tomorrow and see what happens.

Mrmerlin

I would put the maf in another car or put another good MAF into your car

The Forgotten On

Update. I reset the computer and disconnected the maf and the car idles much better while still running pig rich. Time for another MAF.

Jason89s4

Did you ever check your fuel pressure, as previously mentioned? (Test pump on only, at idle/running, and then 20 minute off leak down.)
If you are running rich due to bad pump, FPR's or kinked return line, the best MAF on the planet is not going to fix that.
Might be time for new wires as well....new plugs to replaced the carbon fouled ones (from running rich) while youre in there.
Jason

The Forgotten On

I didn't touch the fuel lines so I doubt anything is kinked. Pump wouldn't affect it running rich due to the FPR doing what it should, a bad pump could make it run lean though.

The wires are only 8 years old and were fine before the battery connection got loose. The car ran great before this.

What should have made me a bit suspicious when I got the rebuilt MAF about 8 months ago is the car started running richer than it had previously according to my nose and indicated fuel economy.

I had just thought the old one failed lean even though it had no problems I knew of with the car running fine before the ISV hoses cracked .

I just thought it was old with over 200K miles on the car at the time and thought it would be prudent to replace it.

I didn't have time to test fuel pressure before it got dark, but with the car running so much better with the maf unplugged I don't think it was fuel pressure related.

Mrmerlin

NOTE if the O2 sensor is old you would be wise to replace it

Jason89s4

Blake,
To clarify, I'm not suggesting that you did anything with the fuel lines. You did just take a 500+ mile trip. My suggestion was to inspect your return line, particularly on the soft underbelly of your vehicle underneath the rear passenger seat where the line loses the frame rail protection. One of the purposes of the pressure test with pump jumpered is to check for the kinked line. (According to WSM, if you clamp the return line, your pump alone will cause pressure to reach at least 4 bar.)
Also, I'm not sure how you know if "the FPR doing what it should do" unless you check the fuel pressure?

Further, double check the connector and pins at the MAF plug, particularly if you have done a lot of plugging/unplugging, which is sounds to be the case. (I had an identical issue...car fired right up, idled perfectly purring like a kitten, then as soon as you touched the throttle it missed, ran rich, you had to feather it to even bring the rpms up. It was a single pin on the MAF plug connector that had come loose. Fixed it, problem solved.)
Let us know,
Jason

The Forgotten On

It was replaced at the same time as the MAF was. So it's about 8 months old.

The Forgotten On

I've inspected the lines and they are fine under the car and in the engine bay. The pins in the maf plug are solidly in place and don't move nor do they short according to my multimeter.

The failure was electronic in nature originally but the car has been having parts go bad left and right after I got its DD replacement so I'll give everything a closer once over.

dr bob

Blake & the group --

It's easy and common to mistake a too-lean misfire condition for too rich. Unburned fuel passes through, and gives a fuel-smelling exhaust until the cat get [really] hot. Rich Andrade does the MAF services in addition to the controller diagnostics and rebuld. Roger offers the MAF connector body, boot, and pins if you want to make it like new again.