LIMP MODE/ 4 CYL MODE
11-06-2005, 08:20 PM
#1
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LIMP MODE/ 4 CYL MODE
Do pre S4 Sharks have the "limp mode"? Still t-shooting my gremlin, and read a few threads mentioning the 4 cyl mode/limp mode. Sounds similar to my problem. It runs fine for several miles, but when it heats up the enigine feels weak and runs like it's mis-firing 
Last edited by Darien; 11-06-2005 at 08:39 PM.
11-06-2005, 08:49 PM
#2
928 Collector
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No Darien. You have 8 sparks and if there aren't 8, then check where there are no sparks. You'll find that dead sparkplugs/wires/connectors/distributor cap/coil/coil wire/rotors will do that. Also water on the spark plugs in the chamber will do that.
11-06-2005, 08:54 PM
#3
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Darien,
No "limp home" mode on the pre S4's.
If it seems to only happen after several components 'warm up', have you looked into a coil going bad or a cracked cap and/or rotor. Did you change the wires yet? I would also clean any of the grounds you can get to. Check the main ground strap under the engine, and maybe the coil grounds as well.
Jim
No "limp home" mode on the pre S4's.
If it seems to only happen after several components 'warm up', have you looked into a coil going bad or a cracked cap and/or rotor. Did you change the wires yet? I would also clean any of the grounds you can get to. Check the main ground strap under the engine, and maybe the coil grounds as well.
Jim
11-06-2005, 09:00 PM
#4
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Are there signs of a coil going bad or do they just go bad?
I'm waiting for my new wires, and have re-checked the plugs, they look normal. The rotors and caps are 6 months old. I'll start searching for Ground wires while in the holding pattern
DAMN GREMLIN
I'm waiting for my new wires, and have re-checked the plugs, they look normal. The rotors and caps are 6 months old. I'll start searching for Ground wires while in the holding pattern
DAMN GREMLIN
11-06-2005, 09:28 PM
#6
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Originally Posted by Jim R.
No "limp home" mode on the pre S4's.
Darien, limp home runs all 8 cylinders, just extremely rich above idle. Somebody (Jim B?) explained it to me as the fuel map changing to only two possibilities... idle and WOT. If you're not idling, it provides enough fuel for WOT.
If you're running on 4-cylinders there are three possibilities, a coil/rotor/cap/coilwire is bad, one bank of injectors is not receiving 12V, one bank of injectors is not being grounded (fired) by the LH. To figure out if it's fuel or spark, do what I recommended before... with the car running pull and reconnect one injector connector at a time to figure out which cylinders are not firing. No change = not firing. Worse running = good and firing. If they are all on one side, it's fuel. If they are two on each side matching the distributer diagram on top of your radiator, it's spark.
11-06-2005, 09:29 PM
#7
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Do you have a timing light? If so you can check to see if each cylinder is firing. Or at least find the one/ones that isn't. Check your final stages up front. It could be that as they are heating up you are losing spark to four cylinders. There is a heat sink paste between them and the area they are bolted too. It is twenty years old and most likely dried out and not transfering the heat like it should.
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11-06-2005, 09:34 PM
#8
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Get the engine to its misfire mode close to home a lift the hood in the dark of night. If the wires are bad you'll have quite the light show as the ignition wires short themselves to the valve covers, cylinder head etc.
11-06-2005, 09:34 PM
#9
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Careful. If you try to pull them they will break open and you'll need to replace them! Darien, two questions:
1) reason to believe anything more than wires is wrong?
2) sure it's 4? Which 4? Or is it 6 or 3?
1) reason to believe anything more than wires is wrong?
2) sure it's 4? Which 4? Or is it 6 or 3?
11-06-2005, 09:37 PM
#10
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Originally Posted by the flyin' scotsman
Get the engine to its misfire mode close to home a lift the hood in the dark of night. If the wires are bad you'll have quite the light show as the ignition wires short themselves to the valve covers, cylinder head etc.
11-06-2005, 09:55 PM
#11
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Originally Posted by heinrich
Darien established in another thread his wires were lighting up like a Christmas tree.
Then the tshooting is over and now the choice of what wires to use as replacements. I have the Nology wires on my car, work very well but quite a few $$$ but I believe 'Shaaark89' was selling a set in his garage sale.
11-06-2005, 10:01 PM
#13
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heinrich, just trying to rule out all my options while waiting for NEW WIRES. Derek sent me his old OEM wires that he changed out around the time he installed his SC, he said they were fine but wanted to start fresh. I installed them last night and it started and idled normal, I didn't have time to drive it the usual distance. On the way to work this morning same story with different wires. I'll check under the hood when I get home tonight while it's mis-firing.
Seems starnge it takes the same amount of time for both sets of wires to fail
Seems starnge it takes the same amount of time for both sets of wires to fail
11-06-2005, 10:29 PM
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Originally Posted by Shane
Do you have a timing light? If so you can check to see if each cylinder is firing. Or at least find the one/ones that isn't. Check your final stages up front. It could be that as they are heating up you are losing spark to four cylinders. There is a heat sink paste between them and the area they are bolted too. It is twenty years old and most likely dried out and not transfering the heat like it should.
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Tim
11-07-2005, 12:49 AM
#15
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Well then I'd say you have the misfortune of another problem 
...... Check inside your throttle body (pull the MAF) for fuids. And yes may as well try Mr Dog's suggestion too 
...... Check inside your throttle body (pull the MAF) for fuids. And yes may as well try Mr Dog's suggestion too