Looking for Expert Troubleshooting Advice
mosherup
10-29-2002, 03:01 PM
Hello all.
This is my first time posting to this board, although it's not my first time reading from it. I've seen some really good advice been given, and that's what I'm looking for :). I've got a problem with my 91 Integra that I would like to try and fix myself. The problem is, I don't know what's causing the problem or even how to test different parts of the engine or whatever so I know what I need to work on or replace. I'd really appreciate any advice or help you all can give me on what you think is causing the problem, checks I can do, and/or how to fix it. You may have a good idea based on my concise description directly below, or if you have some more time on your hands, you can skim or read through the more detailed history. I included the history hoping it would give some clues.
******Concise description of problem:*******
Engine stutters between the approximate RPM range 2400-3600. Most noticeable on acceleration, but also occurs with a constant speed. Engine runs more roughly that it used to, and runs slightly hotter than it used to, and seems to lack the amount of power it used to as well. Problem also becomes increasing noticeable as the engine warms up, from hardly noticeable at all when the car is cold, to very noticeable when the car is hot. Within the last week or so I¡¦ve even noticed, or heard mind you, what seems like light backfires.
*******In depth description of problem, car history, parts replaced, and general information that may be helpful to determining what the problem is:******
It¡¦s a 2-door ¡¥91 Acura Integra LS Special, 5-speed. It has a 1.8L DOHC Non-VTEC Engine in it with unknown mileage. I purchased the car used in 2001, and have had it since then. It does not have its factory engine, although it does have the same type of engine that it should have. The original owner of the car ran it through some deep water and ruined its original engine. It was replaced by an engine out of another ¡¥91 Integra that had been totaled (all but the engine). The original owner was told that the replacement engine had 95k miles on it, but you never really know. This is why I said the mileage is unknown.
When I first got the vehicle, the only engine problem I noticed was a very slight decrease in power when accelerating, this would happen between about 2750-3000 RPMs. For instance, pressing the accelerator in about half way and holding it constant in 3rd gear from 1000 RPM to 6000RPM there would be a nice smooth acceleration curve from 1000 to 2750, then there was a very slight loss of power from 2750 to 3000, then it would be nice and smooth from 3000 to about 4000 when the ECU kicked in and would give it an additional boost in acceleration, which was also smooth. At first, this slight decrease in acceleration was only noticeable by me. Passengers were not able to tell at that time. I could of coarse, because I was driving, and I know my car. I didn¡¦t worry much about it, I figured maybe that was normal for the car since I had not had the vehicle that long.
Shortly after I obtained the car, I started to do some routine maintenance. Here is what I did:
-Took it in for an oil change, supplied my own oil filter and full-synthetic 10w30 motor oil.
-Replaced the spark plugs with Auto Zone recommended spark plugs for the car. These were 4 AC Delco Rapidfire plugs.
-I noticed an air-intake/vacuum hose was not plugged in, so I plugged it back in.
-Replaced the fuel filter.
-Replaced the air filter with a K&N filter charger.
-Reset the ECU, which is recommended after any changes to the engine setup. (e.g. a higher-flow air filter)
-Ran a bottle of Fuel Injector cleaner through a full tank of gas. I know this was not a good thing to do to a foreign car now, but it did not seem to hurt anything at all. I understand now that only American-made vehicles need fuel injection cleaning every-so-often.
As time progressed, the problem steadily became worse. The loss of power RPM range expanded to about 2600-3100, and the stuttering slightly began within that RPM range. About 2 months ago (July/August, 2002), it got to the point where the stuttering was happening from about 2500-3500 RPM, and it happens that 5th gear driving 60-65 MPH that the RPM needle is in that range. It was to the point where I thought it was going to leave me on the side of the road. The surging and stuttering made me nervous. So I took it to an import specialization repair shop.
Here¡¦s the story about the repair shop where I got screwed (yeah, I¡¦m a dumbass): I brought it in, they said they would take a look at it for $32 and that would be waved if I decided to have them repair the problem (if they could find it). An hour passes by and they come back and tell me they don¡¦t know what¡¦s wrong with it, so they want to hook it up to some computer system they have and check things out. This will cost me $65 just for the test. I ended up letting them run the test thinking they would find and fix the problem. Another hour or so passes and they come back and tell me they found 2 engine codes. #1 low oil; I knew this one because the engine slowly burns or leaks oil, and I forgot to check it after a couple months went by and the engine light flashed on me one day. I checked the oil, and sure enough, it was low. #2 engine stall; I knew of this one as well because I was passing a semi one day in 2nd gear (had to get by him real fast) and I accidently ran it into the redline ~6500 RPM. This particular car, which I found out later, has a governor set at ~6400 RPM controlled by the ECU. So it kicked in while I was passing the semi and I got an engine light after the engine stalled. Anyway, they told me that it was inconclusive but they noticed the distibutor rotor was worn and the O-ring was slightly leaking oil (which was just running down the side of the engine). I asked if that¡¦s what could be causing the problem and they said yes. They wanted $80 alone to replace the O-ring, and I figured I could get away with the leak so I told them to leave it be. But I did let them to go ahead and replace the rotor and the distributor cap thinking that would fix my problem. They also didn¡¦t like my AC Delco Rapidfire plugs, and recommended I let them put Honda¡¦s recommended plugs in (can¡¦t remember the name of them at the moment), and for some reason I said go ahead. After 4 hours of being in the waiting room, they came back in and said it was ready for me. They told me that they fixed it, so I took it home. The final bill came to $180, and they DID NOT fix my problem, only masked it. I found this out on the drive home (hour drive). I mean $180 was steep even if they did fix it. Now I noticed it wasn¡¦t the same as when I had brought it in, it was like they removed about 2 months on time off the progression of the problem, and I bet I know what they did. It¡¦s only an assumption, but it seems all they did was advance the amount of fuel being pumped into the engine under acceleration. Why, you ask? Because even to this day, pressing the gas petal in more than just a little bit before it reaches over 3k RPM makes the engine want to die, like it¡¦s being choked (heh heh). Seriously, it seems like it¡¦s running to rich, even to this day. This was not a problem at all before I took it to these people. The side effect is that it did help to mask the stuttering. The stuttering reduced, as did the RPM range that it would seem to occur within. Anyway, after some curse words, and beating my head into the wall a few times I sucked it up and dealt with it. It was better than it was before, and more driveable than previously, so I continued.
Still the problem worsened, back to about how it was before I took it to that repair shop.
A few weeks later: Removed factory muffler, and replaced it with a TegWeld straight-through design muffler to help it breathe.
Problem has continued getting worse, and now I fear it will not stop getting worse and it¡¦s going to leave me on the side of the road somewhere one day. So now we¡¦re at the present time, and repeating what I said at the very top of this book about the concise problem: ¡§Engine stutters between the approximate RPM range 2400-3600. Most noticeable on acceleration, but also occurs with a constant speed. Engine runs more roughly that it used to, and runs slightly hotter than it used to, and seems to lack the amount of power it used to as well. Problem also becomes increasing noticeable as the engine warms up, from hardly noticeable at all when the car is cold, to very noticeable when the car is hot. Within the last week or so I¡¦ve even noticed, or heard mind you, what seems like light backfires.¡¨
So now I¡¦m looking for some help. I really don¡¦t want to take it back to another repair shop to get screwed again. Damnit, if a specialist shop can¡¦t fix it the first time, that¡¦s pretty sad. I¡¦m no car expert, and most of what I know I¡¦ve learned since obtaining this car, but I¡¦m an engineer, so I¡¦m no idiot either. And I¡¦m not afraid to get my hands dirty and try and fix the problem myself as long as it doesn¡¦t cost too much. Money is my main problem here, or I would run it from shop to shop seeing who would be the first mechanic to figure out the problem, but I don¡¦t have that luxury. I purchased the Haynes Manual for the car, and it says under ¡§Troubleshooting: Engine stumbles on acceleration:¡¨ the following causes:
1 Spark plugs fouled (it¡¦s had 2 new sets now with no noticable change, so we can rule this one out)
2 Fuel Injection System faulty (Possibility?)
3 Fuel Filter clogged (I replaced the fuel filter shortly after I got the car, so I think we can rule this one out)
4 Incorrect ignition timing (Possibility? But I reset the ECU, and ignition timing is controlled by the ECU right?)
5 Intake Manifold air leak (Possibility? This one seems like it may be the most logical, but how would you perform a check?)
Also under ¡§Troubleshooting: Engine backfires AND Engine lacks power¡¨ it says:
1 Incorrect ignition timing (Possibility?)
2 Excessive play in distibutor shaft (Hmm, that shop should have noticed this if it was a problem, so we can rule it out I hope)
3 Worn rotor, distributor cap or wires (Shop replaced everything but the wires, I guess I could replace those, but I don¡¦t think they are the problem?)
4 Faulty or incorrectly gapped spark plugs (see above)
5 Fuel injection system out of adjustment or excessively worn (Hmmm, good possibility?)
6 Faulty coil (Possibility?)
7 Brakes binding (nah, unrelated)
8 Automatic transmission fluid level incorrect (wth, it¡¦s a 5-speed)
9 Clutch slipping (pretty sure I could tell if it was a clutch problem)
10 Fuel filter clogged (see above)
11 Emission control system not functioning properly (Possibility?)
12 Catalytic converter plugged (Possibility? But I doubt it)
13 Low or uneven cylinder compression pressures (Possibility?)
14 Obstructed exhaust system (Possibility? But I doubt it)
15 Low fuel pressure caused by misfunctioning fuel pump (Possibility?)
So the question is, what do you think would cause the symptoms of my car/engine¡¦s problem, and how would I go about to check for them without replacing everything.
I¡¦m leaning towards something wrong with the fuel injection system, the coil, the fuel pump, or my worst fear, low or uneven cylinder compression.
What do you think guys? Help! ļ
Thanks again all,
Chris
This is my first time posting to this board, although it's not my first time reading from it. I've seen some really good advice been given, and that's what I'm looking for :). I've got a problem with my 91 Integra that I would like to try and fix myself. The problem is, I don't know what's causing the problem or even how to test different parts of the engine or whatever so I know what I need to work on or replace. I'd really appreciate any advice or help you all can give me on what you think is causing the problem, checks I can do, and/or how to fix it. You may have a good idea based on my concise description directly below, or if you have some more time on your hands, you can skim or read through the more detailed history. I included the history hoping it would give some clues.
******Concise description of problem:*******
Engine stutters between the approximate RPM range 2400-3600. Most noticeable on acceleration, but also occurs with a constant speed. Engine runs more roughly that it used to, and runs slightly hotter than it used to, and seems to lack the amount of power it used to as well. Problem also becomes increasing noticeable as the engine warms up, from hardly noticeable at all when the car is cold, to very noticeable when the car is hot. Within the last week or so I¡¦ve even noticed, or heard mind you, what seems like light backfires.
*******In depth description of problem, car history, parts replaced, and general information that may be helpful to determining what the problem is:******
It¡¦s a 2-door ¡¥91 Acura Integra LS Special, 5-speed. It has a 1.8L DOHC Non-VTEC Engine in it with unknown mileage. I purchased the car used in 2001, and have had it since then. It does not have its factory engine, although it does have the same type of engine that it should have. The original owner of the car ran it through some deep water and ruined its original engine. It was replaced by an engine out of another ¡¥91 Integra that had been totaled (all but the engine). The original owner was told that the replacement engine had 95k miles on it, but you never really know. This is why I said the mileage is unknown.
When I first got the vehicle, the only engine problem I noticed was a very slight decrease in power when accelerating, this would happen between about 2750-3000 RPMs. For instance, pressing the accelerator in about half way and holding it constant in 3rd gear from 1000 RPM to 6000RPM there would be a nice smooth acceleration curve from 1000 to 2750, then there was a very slight loss of power from 2750 to 3000, then it would be nice and smooth from 3000 to about 4000 when the ECU kicked in and would give it an additional boost in acceleration, which was also smooth. At first, this slight decrease in acceleration was only noticeable by me. Passengers were not able to tell at that time. I could of coarse, because I was driving, and I know my car. I didn¡¦t worry much about it, I figured maybe that was normal for the car since I had not had the vehicle that long.
Shortly after I obtained the car, I started to do some routine maintenance. Here is what I did:
-Took it in for an oil change, supplied my own oil filter and full-synthetic 10w30 motor oil.
-Replaced the spark plugs with Auto Zone recommended spark plugs for the car. These were 4 AC Delco Rapidfire plugs.
-I noticed an air-intake/vacuum hose was not plugged in, so I plugged it back in.
-Replaced the fuel filter.
-Replaced the air filter with a K&N filter charger.
-Reset the ECU, which is recommended after any changes to the engine setup. (e.g. a higher-flow air filter)
-Ran a bottle of Fuel Injector cleaner through a full tank of gas. I know this was not a good thing to do to a foreign car now, but it did not seem to hurt anything at all. I understand now that only American-made vehicles need fuel injection cleaning every-so-often.
As time progressed, the problem steadily became worse. The loss of power RPM range expanded to about 2600-3100, and the stuttering slightly began within that RPM range. About 2 months ago (July/August, 2002), it got to the point where the stuttering was happening from about 2500-3500 RPM, and it happens that 5th gear driving 60-65 MPH that the RPM needle is in that range. It was to the point where I thought it was going to leave me on the side of the road. The surging and stuttering made me nervous. So I took it to an import specialization repair shop.
Here¡¦s the story about the repair shop where I got screwed (yeah, I¡¦m a dumbass): I brought it in, they said they would take a look at it for $32 and that would be waved if I decided to have them repair the problem (if they could find it). An hour passes by and they come back and tell me they don¡¦t know what¡¦s wrong with it, so they want to hook it up to some computer system they have and check things out. This will cost me $65 just for the test. I ended up letting them run the test thinking they would find and fix the problem. Another hour or so passes and they come back and tell me they found 2 engine codes. #1 low oil; I knew this one because the engine slowly burns or leaks oil, and I forgot to check it after a couple months went by and the engine light flashed on me one day. I checked the oil, and sure enough, it was low. #2 engine stall; I knew of this one as well because I was passing a semi one day in 2nd gear (had to get by him real fast) and I accidently ran it into the redline ~6500 RPM. This particular car, which I found out later, has a governor set at ~6400 RPM controlled by the ECU. So it kicked in while I was passing the semi and I got an engine light after the engine stalled. Anyway, they told me that it was inconclusive but they noticed the distibutor rotor was worn and the O-ring was slightly leaking oil (which was just running down the side of the engine). I asked if that¡¦s what could be causing the problem and they said yes. They wanted $80 alone to replace the O-ring, and I figured I could get away with the leak so I told them to leave it be. But I did let them to go ahead and replace the rotor and the distributor cap thinking that would fix my problem. They also didn¡¦t like my AC Delco Rapidfire plugs, and recommended I let them put Honda¡¦s recommended plugs in (can¡¦t remember the name of them at the moment), and for some reason I said go ahead. After 4 hours of being in the waiting room, they came back in and said it was ready for me. They told me that they fixed it, so I took it home. The final bill came to $180, and they DID NOT fix my problem, only masked it. I found this out on the drive home (hour drive). I mean $180 was steep even if they did fix it. Now I noticed it wasn¡¦t the same as when I had brought it in, it was like they removed about 2 months on time off the progression of the problem, and I bet I know what they did. It¡¦s only an assumption, but it seems all they did was advance the amount of fuel being pumped into the engine under acceleration. Why, you ask? Because even to this day, pressing the gas petal in more than just a little bit before it reaches over 3k RPM makes the engine want to die, like it¡¦s being choked (heh heh). Seriously, it seems like it¡¦s running to rich, even to this day. This was not a problem at all before I took it to these people. The side effect is that it did help to mask the stuttering. The stuttering reduced, as did the RPM range that it would seem to occur within. Anyway, after some curse words, and beating my head into the wall a few times I sucked it up and dealt with it. It was better than it was before, and more driveable than previously, so I continued.
Still the problem worsened, back to about how it was before I took it to that repair shop.
A few weeks later: Removed factory muffler, and replaced it with a TegWeld straight-through design muffler to help it breathe.
Problem has continued getting worse, and now I fear it will not stop getting worse and it¡¦s going to leave me on the side of the road somewhere one day. So now we¡¦re at the present time, and repeating what I said at the very top of this book about the concise problem: ¡§Engine stutters between the approximate RPM range 2400-3600. Most noticeable on acceleration, but also occurs with a constant speed. Engine runs more roughly that it used to, and runs slightly hotter than it used to, and seems to lack the amount of power it used to as well. Problem also becomes increasing noticeable as the engine warms up, from hardly noticeable at all when the car is cold, to very noticeable when the car is hot. Within the last week or so I¡¦ve even noticed, or heard mind you, what seems like light backfires.¡¨
So now I¡¦m looking for some help. I really don¡¦t want to take it back to another repair shop to get screwed again. Damnit, if a specialist shop can¡¦t fix it the first time, that¡¦s pretty sad. I¡¦m no car expert, and most of what I know I¡¦ve learned since obtaining this car, but I¡¦m an engineer, so I¡¦m no idiot either. And I¡¦m not afraid to get my hands dirty and try and fix the problem myself as long as it doesn¡¦t cost too much. Money is my main problem here, or I would run it from shop to shop seeing who would be the first mechanic to figure out the problem, but I don¡¦t have that luxury. I purchased the Haynes Manual for the car, and it says under ¡§Troubleshooting: Engine stumbles on acceleration:¡¨ the following causes:
1 Spark plugs fouled (it¡¦s had 2 new sets now with no noticable change, so we can rule this one out)
2 Fuel Injection System faulty (Possibility?)
3 Fuel Filter clogged (I replaced the fuel filter shortly after I got the car, so I think we can rule this one out)
4 Incorrect ignition timing (Possibility? But I reset the ECU, and ignition timing is controlled by the ECU right?)
5 Intake Manifold air leak (Possibility? This one seems like it may be the most logical, but how would you perform a check?)
Also under ¡§Troubleshooting: Engine backfires AND Engine lacks power¡¨ it says:
1 Incorrect ignition timing (Possibility?)
2 Excessive play in distibutor shaft (Hmm, that shop should have noticed this if it was a problem, so we can rule it out I hope)
3 Worn rotor, distributor cap or wires (Shop replaced everything but the wires, I guess I could replace those, but I don¡¦t think they are the problem?)
4 Faulty or incorrectly gapped spark plugs (see above)
5 Fuel injection system out of adjustment or excessively worn (Hmmm, good possibility?)
6 Faulty coil (Possibility?)
7 Brakes binding (nah, unrelated)
8 Automatic transmission fluid level incorrect (wth, it¡¦s a 5-speed)
9 Clutch slipping (pretty sure I could tell if it was a clutch problem)
10 Fuel filter clogged (see above)
11 Emission control system not functioning properly (Possibility?)
12 Catalytic converter plugged (Possibility? But I doubt it)
13 Low or uneven cylinder compression pressures (Possibility?)
14 Obstructed exhaust system (Possibility? But I doubt it)
15 Low fuel pressure caused by misfunctioning fuel pump (Possibility?)
So the question is, what do you think would cause the symptoms of my car/engine¡¦s problem, and how would I go about to check for them without replacing everything.
I¡¦m leaning towards something wrong with the fuel injection system, the coil, the fuel pump, or my worst fear, low or uneven cylinder compression.
What do you think guys? Help! ļ
Thanks again all,
Chris
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