Hesitation, crackling noise similar to pinging, no acceleration in 5th.
04-03-08 | 04:31 AM
#1
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From: Undercity
Hesitation, crackling noise similar to pinging, no acceleration in 5th.
Car: 86 NA 104,000 miles
History: I've always had the 3800 rpm hesitation but the car always pulled strong. I've only really pushed it a few times just to see what it would do (I bought it with 97,000 miles) and in 4rth gear when I'd get over 5k rpms I would hear a crackling noise at WOT similar to pinging in a piston engine and if I eased off the gas just a little it would go away but the car still pulled. I only stressed the car like this 2 or 3 times as this is not my race car, just a fun commuter that I like to work on. When I bought the car it would randomly die, and I found that the issue was corroded positive/negative connecters to the battery. I got dielectric grease and a wire brush and it solved that issue, however the cables aren't in good shape. Every once in a while I will start the car and the voltage meter will not come on for a good while. Otherwise car has allways had good torque down low. One last thing, the car was missing a piece of hose that ran from the intake housing to the smog pump, and the smog pump opening had a paper towel wrapped around it secured with a rubber band. I drove it around like this the whole time and got a hose connected when I had to smog the car. It passed smog, but I heard this could have clogged the cat (running it without the tube from the intake)
My current problem: I stalled the car a couple of days ago immediately after starting it up and a few times last week I let off the clutch too early and the car practically died but stayed on (all the idiot lights flashed for a sec but the car didn't die, just barely). Now, when I'm on the freeway, I have no torque in 5th and I can't seem to get above 80mph in 5th. As soon as I approach 70-80 mph and I'm giving it 3/4 to wot, I hear a crackling noise that sounds similar to pinging in a piston engine. At this speed the rpms are well below 3800, they are actually around the 3100 range. If I give it 1/2 throttle and slowly accelerate the noise is not present but the acceleration hits a wall. If I drop it to fourth gear at 70-80 mph my rpms will be a bit over 4k but I dont hear the crackling unless I go WOT. I tried to listen for the noise going WOT in the lower gears and at first it wasn't present but now I can hear it going WOT in 2nd and 3rd. On 1 out of every 4 days at some point in the day the car will be normal and will haul a$$ on the freeway and will hit 80-90 mph no problem. This will only last for a portion of the day and it will go back to sucking butt.
I've spent the last 3 hours reading every thread (41 of them) for the search term "bogging". Most of the suggestions were either ignition or fuel related. Everything from changing spark plugs to running rich to changing the fuel filter to redoing the grounds to throttle linkage to injectors to fuel pump to ecu to secondary injector connection to oil pressure sender. Now, I'm good with a wrench, almost all of my installation experience is with suspension (bushings, shocks, springs, shock inserts, camber kits, swaybars, adjustable control arms). I have only done a few things on an engine, which includes changing a fan clutch and replacing a bad starter. I am completely overwhelmed with what to do and where to start. What would be the best/easiest/most logical place to start? Should I just take my car to a shop? I like to do work like this myself because I like to keep track of the repairs and its easier to find parts that are about to give out if I do the work myself. Any advice is greatly appreciated. I've been skimming over the FSM and it just seems so scary to me.
History: I've always had the 3800 rpm hesitation but the car always pulled strong. I've only really pushed it a few times just to see what it would do (I bought it with 97,000 miles) and in 4rth gear when I'd get over 5k rpms I would hear a crackling noise at WOT similar to pinging in a piston engine and if I eased off the gas just a little it would go away but the car still pulled. I only stressed the car like this 2 or 3 times as this is not my race car, just a fun commuter that I like to work on. When I bought the car it would randomly die, and I found that the issue was corroded positive/negative connecters to the battery. I got dielectric grease and a wire brush and it solved that issue, however the cables aren't in good shape. Every once in a while I will start the car and the voltage meter will not come on for a good while. Otherwise car has allways had good torque down low. One last thing, the car was missing a piece of hose that ran from the intake housing to the smog pump, and the smog pump opening had a paper towel wrapped around it secured with a rubber band. I drove it around like this the whole time and got a hose connected when I had to smog the car. It passed smog, but I heard this could have clogged the cat (running it without the tube from the intake)
My current problem: I stalled the car a couple of days ago immediately after starting it up and a few times last week I let off the clutch too early and the car practically died but stayed on (all the idiot lights flashed for a sec but the car didn't die, just barely). Now, when I'm on the freeway, I have no torque in 5th and I can't seem to get above 80mph in 5th. As soon as I approach 70-80 mph and I'm giving it 3/4 to wot, I hear a crackling noise that sounds similar to pinging in a piston engine. At this speed the rpms are well below 3800, they are actually around the 3100 range. If I give it 1/2 throttle and slowly accelerate the noise is not present but the acceleration hits a wall. If I drop it to fourth gear at 70-80 mph my rpms will be a bit over 4k but I dont hear the crackling unless I go WOT. I tried to listen for the noise going WOT in the lower gears and at first it wasn't present but now I can hear it going WOT in 2nd and 3rd. On 1 out of every 4 days at some point in the day the car will be normal and will haul a$$ on the freeway and will hit 80-90 mph no problem. This will only last for a portion of the day and it will go back to sucking butt.
I've spent the last 3 hours reading every thread (41 of them) for the search term "bogging". Most of the suggestions were either ignition or fuel related. Everything from changing spark plugs to running rich to changing the fuel filter to redoing the grounds to throttle linkage to injectors to fuel pump to ecu to secondary injector connection to oil pressure sender. Now, I'm good with a wrench, almost all of my installation experience is with suspension (bushings, shocks, springs, shock inserts, camber kits, swaybars, adjustable control arms). I have only done a few things on an engine, which includes changing a fan clutch and replacing a bad starter. I am completely overwhelmed with what to do and where to start. What would be the best/easiest/most logical place to start? Should I just take my car to a shop? I like to do work like this myself because I like to keep track of the repairs and its easier to find parts that are about to give out if I do the work myself. Any advice is greatly appreciated. I've been skimming over the FSM and it just seems so scary to me.
04-03-08 | 05:41 AM
#2
Any number of things could cause the problem. I would start as simple as posible. You found croded battery conections before. I would reground everything in the engine bay. Its free and easy, it might even fix the problem.
This is the best write-up I have seen for doing the grounds.
http://www.aaroncake.net/rx-7/grounding.htm
After that I would see if your ecu is throwing any codes. Since you have a S4, you will have to rig up a 2 LED checker. Do a search for "ecu codes" or "code puller" or anything if that natural and you should find a write-up for it.
my 2 cents.
This is the best write-up I have seen for doing the grounds.
http://www.aaroncake.net/rx-7/grounding.htm
After that I would see if your ecu is throwing any codes. Since you have a S4, you will have to rig up a 2 LED checker. Do a search for "ecu codes" or "code puller" or anything if that natural and you should find a write-up for it.
my 2 cents.
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