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I did have Big's GTS AUTO tuned to over 300rwhp with one of our crossovers and it had stock cams.
Dyno sheets are readily available to back up the stated horsepower and torque gains. All of my dyno testing was done on the same dyno, the same day, the same car without even removing all the tie down straps. NO fuel tuning was done so I am certain that there was even more to be had than what was shown.
The attached dyno sheet was on an 86.5' 5-speed, notice where the gains start and the midrange torque gains.
Give it a shot, but...I think we are angling in on the same desired outcome. I ran mine for a while with x, 100cpi, aftermarket mids and the stock rear muffler. It sounded decent but overall was still very quiet- the final muffler really does do a crazy job of stifling the sound.
I replaced the final muffler with an aftermarket akin to that in Roger's dual setup..and now it is too loud for my taste...just cats and final muffler might be one way to go, though I don't think the stock or my aftermarket mids are doing much to reduce dB/SPL.
Maybe some day Ken or someone else will get into surgery on the factory muffler and come up with 'three bears' options...no internals, no packing but baffles retained, and moderate strip out of packing only.
Doubt anyone will see this but I have an 89 S4 really stinks one 928 guy has said he has never seen one go bad. So mine stinks and we have tried everything else. any thoughts.
Doubt anyone will see this but I have an 89 S4 really stinks one 928 guy has said he has never seen one go bad. So mine stinks and we have tried everything else. any thoughts.
Everyone will see it, a new post brings an old thread back from the dead. But no one will understand your question.
My suggestion is to start a new thread and introduce yourself, explain what you are concerned about, and add some details about the car-- has it been modified at all, or completely stock??
And of course, pictures of the car are always nice.
Completely stock 1989 S4. 106,000 miles. Have a horrible unburnt fuel smell have spent a ridiculous amount of money trying to make it go away. Had brain rebuilt all vacuum lines all rubber on engine. I saw this individual mention the cats and he is the second in as many weeks where I saw the comment. Another mechanic said I have never seen a 928 cat go bad. I would love to find one as it is about the last resort. I am embarrassed to say how much I have spent on this car already. Picture
Completely stock 1989 S4. 106,000 miles. Have a horrible unburnt fuel smell have spent a ridiculous amount of money trying to make it go away. Had brain rebuilt all vacuum lines all rubber on engine. I saw this individual mention the cats and he is the second in as many weeks where I saw the comment. Another mechanic said I have never seen a 928 cat go bad. I would love to find one as it is about the last resort. I am embarrassed to say how much I have spent on this car already. Picture
You need a better approach. Install a wide band O2. That will allow you to see what is going on in real time.
Some examples (no comprehensive)...
if it's close to stoichiometric during warm up and rich when hot that would point to a problem in the warm up system.
If it idles closer to stoichiometric with MAF un plugged then you may have a problem in the MAF circuit.
BTW, I have a well tuned 928 with no cats and it has no smell once warmed up. It's a bit rich during warm up as to be expected.
Great looking car, thanks for the photo. Now we need a shot of the engine bay, folks here are funny that way.
I am not sure a wideband is needed. The nose does a good job of detecting too rich, but not too rich to run-- so probably 12:1 AFR. The factory cats are quite robust, the guy that said "they never fail" knew that much but not how to isolate the problem. And no cat will fix an always-too-rich problem. cats need some excess-O2, and a rich mixture hasn't got any.
Don't sweat the LH rebuild, if it was original then that was needed anyway to avoid a future failure. (The '87-95 LH ECUs have a small ceramic hybrid circuit which will eventually fail). Same with the rubber bits, they will be needed at some point, so a good investment. Just don't be fooled into thinking that just because the cars have depreciated and typically sell for a fraction of their original price, that the parts will be similarly discounted.
It could be the MAF (airflow sensor) or the O2 sensor. If either is original at 106K miles, then they are due for replacement. The lifetime for an O2-sensor is a little over 60K miles, that being the original emissions warranty. MAFs also age and are usually out of calibration and due for rebuild by 80K miles, but that varies greatly depending on how the car is used-- it depends on total burnoff cycles which happen each time the engine is shut off.
Any good 928-specialist shop will have a diagnostic tester (Bosch "Hammer" or other tester) to check for any codes, and spare brains and a MAF for testing. So you may need to find another shop, and if you want to dive in yourself then there is lots of help here.
Where are you located? And how long have you had the car?
Doubt anyone will see this but I have an 89 S4 really stinks one 928 guy has said he has never seen one go bad. So mine stinks and we have tried everything else. any thoughts.
Unburned fuel points to ignition and/or mechanical issues. Look at the plugs to see if you find some wet after a brief run. Use your IR temp checker on exhaust ports, looking for cold ones. On your '89, the ignition protection relay should be functional. Raw fuel dumping into functional cats equals overheating cats and a car fire.
Done your basic ignition maintenance? (plugs-caps-rotors) At 106k, you are well past due for that, including new plug wires. Check the compression while you have all the plugs out. Pull the EZK (ignition) fuse to protect the ignition system and stop the fuel pump while compression testing. VERIFY the individual plug wire routing, as it's too easy to cross them and have a couple cylinders dropped out.
The car was equipped with sample pipes from the exhaust collectors up into the engine bay. Look for blue caps at the sides of the air filter housing. Exhaust gas there are pre-cat, and will tell you a lot via gas analyzer.
Partially blocked injectors can cause lean misfire, which smells like too much fuel but is the opposite. Plugs and the IR exhaust temp measurement will tell you this.
[QUOTE=rnanaples;17429875]Completely stock 1989 S4. 106,000 miles. Have a horrible unburnt fuel smell have spent a ridiculous amount of money trying to make it go away. Had brain rebuilt all vacuum lines all rubber on engine. I saw this individual mention the cats and he is the second in as many weeks where I saw the comment. Another mechanic said I have never seen a 928 cat go bad. I would love to find one as it is about the last resort. I am embarrassed to say how much I have spent on this car already.
My guess would be the Y pipe. The plastic ones always fail and leak gas fumes. Simple cheap fix. It's all part of the evaporative emissions system. It will make your garage smell like a bucket of gas is sitting in the corner. I bet you a dollar this will fix it.
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