I own a 1991 Caprice with a 5.0 engine. I need to know if a loose connection on a knock sensor could cause a ignition misfire when the car is in closed loop operation. the car runs great when cold but after it warms up to full opp. temp. and I put a load on the engine I get a ignition misfire all 8 cylinders cut in and out. so if you could please let me know what the symptoms of a loose connector on a knock sensor would be. Thanks!
2006-12-30 07:10:56 · 10 answers · asked by Lots of money but no sense 2 in Cars & Transportation ➔ Car Makes ➔ Chevrolet
the only symptom of a loose conection on a knock sensor would be pinging. a knock sensor generates its own voltage, the pcm just listens for the knock sensor saying somethings wrong, but expects nothing if its good. also, a knock senser tells the computer to retard the timeing, and can not cause it to completly cut out.
2006-12-31 03:45:54 · answer #1 · answered by andrew b 2 · 1⤊ 0⤋
A fault from the knock sensor should only retard the timing by up to 10º, which should mean a reduction in power and not a misfire.
First get the codes out of the computer (most workshop manuals will tell you how to do this without special tools) and see what's indicated. If nothing, then I would be looking at the oxygen sensor. It may be indicating rich and leaning the vehicle to the point where it misfires. This could be dangerous to the engine so it needs to be fixed.
By closed loop, do you mean diagnostic mode? The Oxygen sensor is excluded in diagnostic mode. The oxygen sensor is ignored during cold start and usually brought into play after about 9-12 minutes if the temp sensor indicates that the engine is at normal operating temperature.
On another track, I have seen ignition coils fail at operating temperature, so never ignore the basics! If it's misfiring, maybe it is the basic ignition system. Components that commonly fail with heat are coils mounted on the engine and distributor sensors (pickups).
Fuel pressure is unlikely to only be affected at full operating temperature.
Hope this helps.
2006-12-30 15:20:23 · answer #2 · answered by teef_au 6 · 0⤊ 1⤋
As with the poster above I have seen the ignition coil break down when it gets hot... I have also seen the pickup module do the same thing. Good cold bad hot. Also the knock sensor wont cause a misfire like that so you can eliminate that. The coils or the module or fuel is where your problem lies. DONT BUY COILS OR MODULES FROM ADVANCE AUTO PARTS THEY SUCK... I use to manage that place then i managed several automotive shops. they always go bad.. .if they are not already bad when you buy them. Good Luck Have fun
2006-12-31 01:07:00 · answer #3 · answered by Chris 2 · 0⤊ 0⤋
Could be that your plug wires need to be replaced as they could be electicaly tracking to ground on the outside of the plugs on load.A knock sensor is to retard spark upon load.It is possible if it isn`t working correctly that you might exsperience a lag in acceleration and have a missfire.I recomend applying plug grease on ends of plugs and inside plug caps.Also replace cap and rotor.
2006-12-31 01:02:41 · answer #4 · answered by (A) 7 · 0⤊ 1⤋
Start by plugging in the scanner and reading any error codes stored. That will give you the starting point. If it's affecting all cylinders, I'd bet fuel pressure problems.
2006-12-30 15:17:47 · answer #5 · answered by oklatom 7 · 0⤊ 0⤋
this reminds of me of a used Cady i picked up real cheap. after spending several more $$ than I paid for it ,I found a loose ground wire to the computer was loose. It seemed who ever took the radio out ,left the nut loose.
2006-12-30 15:14:43 · answer #6 · answered by Anonymous · 0⤊ 0⤋
i'd say its fuel too just crawl under and ck the pigtail connector and see if its loose as far as the knock sensor goes
2006-12-30 15:21:19 · answer #7 · answered by michael_stewart32 4 · 0⤊ 0⤋
coil pack is breaking down when getting hot.
2006-12-30 19:21:49 · answer #8 · answered by kbandit_2001 1 · 1⤊ 0⤋
buy a ford
2006-12-30 16:17:34 · answer #9 · answered by kenandwei 2 · 0⤊ 4⤋
new car
2006-12-30 15:11:56 · answer #10 · answered by Anonymous · 0⤊ 4⤋