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1991 Acura Integra Stumble on acceleration

Home Forums Stay Dirty Lounge Service and Repair Questions Answered Here 1991 Acura Integra Stumble on acceleration

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  • #435270
    CrUnChCrUnCh
    Participant

      This car has the B18A1 engine with 198,000 miles. It is all stock and burns some oil. It will start and run ok until the normal operating temperature is reached then it acts like an unruly teenager or a spoiled brat 2 year old. After sitting at a red light for a couple of minutes the car wants to stumble and stall instead of accelerating normally. If I manipulate the gas pedal just right I can prevent the car from stalling and proceed down the road. I checked the fuel pressure and it read 30 PSI when the key is turned on and also when it idles. When I open the throttle the fuel pressure rises to 40 PSI. When I disconnect the vacuum line to the fuel pressure regulator the fuel pressure also rises to 40 PSI. I removed the throttle body and cleaned it with carburetor cleaner and reinstalled. I sprayed carb cleaner all around the vacuum lines, intake manifold gasket and throttle body gasket but found no leaks. I measured the throttle position sensor with an ohmmeter while opening the throttle plate slowly. It was linear throughout its range with no dead spots. I removed the idle air control valve and cleaned the dirty screen with carb cleaner and then reinstalled. I opened the fast idle thermo valve and adjusted the inner washer fully clockwise and resealed. Then I bled the cooling system. I checked to see if there were any codes stored in the computer but found none. What should I check next?

    Viewing 15 replies - 1 through 15 (of 19 total)
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    • #435271
      BigCBigC
      Participant

        Hi CrUnCh,

        Great info in your post. Sounds like you have checked and verified that a lot of the components appear to be in proper working order. How about the coolant temperature sensor? A bad coolant temperature sensor might produce the symptoms you are experiencing. If the sensor is open and is sending a signal to the computer that it is say -40F, the ECU will richen the fuel ratio upon start up. No problems are noticed when the engine is started cold. However, as the engine warms up, the air/fuel ratio needs a leaner mixture of fuel. If the coolant temperature sensor is still sending the single to the computer that “hey, I am still cold”, the computer will continue to provide a richer mixture of fuel.

        If this is the case, you might be able to see and/or smell unburnt fuel, especially as you throttle your way from a red light. An ohm meter across the leads of the coolant temperature sensor might provide insight. Also, check the integrity of the wire(s) for this sensor too. As always, isolate the electrical component from the vehicle’s electrical system prior to connecting the ohm meter to the sensor. Good luck and keep us posted.

        #435272
        Trcustoms719Trcustoms719
        Participant

          +1 on testing the ECT (engine coolant temp) sensor.

          #435273
          CrUnChCrUnCh
          Participant

            Thanks for the help guys. I disconnected the electrical connector from the coolant temperature sensor and I measured the resistance of the coolant temperature sensor with the engine cold. I set the ohms scale on my DVM to 200 and it measured open or infinite resistance. I connected the electrical connector back to the temperature sensor and then started the car and let it idle until the normal operating temperature was reached. I then shut off the engine and disconnected the electrical connector from the temperature sensor. I measured the resistance of the temperature sensor again and it read 325 ohms. I then turned the key to the on position without starting the engine and measured the voltage on the electrical connector and it read 4.98 VDC. What should I check next?

            #435274
            Trcustoms719Trcustoms719
            Participant

              The ETC could still be bad, I would see about getting a ohm’s chart for it to see if it’s within specs.

              #435275
              dreamer2355dreamer2355
              Participant

                It would only have a 5vRef if it was a 3 wire ECT and most are 2 wire thermistors. W;)

                You can use a DVOM and run the vehicle with the ECT connector disconnected. Then use your DVOM and see if the resistance chances as temperature increase.

                Alot of misfires or stumbles can be down to ignition misfires.

                Will the vehicle try to stall if you leave it in neutral?

                #435276
                Trcustoms719Trcustoms719
                Participant

                  I wish i could find the ohm’s chart.
                  I can’t find one for this.
                  If the resistance changes with the temp changes like dreamer said, the sensor is probably ok.

                  #435277
                  dreamer2355dreamer2355
                  Participant

                    Here is a basic generic one if the link works –

                    http://0.tqn.com/d/autorepair/1/0/I/A/41928895.gif

                    #435278
                    Trcustoms719Trcustoms719
                    Participant

                      Cool, that should be ok.

                      #435279
                      CrUnChCrUnCh
                      Participant

                        Thanks again guys for all the assistance. I printed a copy of the chart for temperature sensors that was given to me by dreamer for reference. I started the engine and then disconnected the electrical connector from the temperature sensor. I connected the DVOM to the sensor terminals and set the range to the 2000 ohms scale. I watched both the readout from the DVOM and the dashboard temperature gauge while the engine was at idle. As the temperature needle began to rise on the dash the ohms began to drop from a reading of 1401. After about 15 minutes the normal operating temperature was reached and the fans switched on at the radiator. The lowest reading that I observed from the DVOM at that time was 167 ohms. When the fans would cycle off the reading on the DVOM would rise to 230 ohms. Then the fans would turn on and the cycle would repeat. What should I check next?

                        #435280
                        CrUnChCrUnCh
                        Participant

                          To answer the question. The car will stumble and stall if left in neutral.

                          #435281
                          BigCBigC
                          Participant

                            Does your vehicle has good acceleration? A plugged exhaust (catalytic converter) could create backpressure to the point that it affects the operation of the vehicle at idle (and when driving). A vacuum gauge can help with this determination. The vacuum at idle should be ~ 18 inches of Hg (mercury). With the car at idle for a while, see if the vacuum steadily decreases. This would support a plugged or partially blocked exhaust (usually due to a plugged catalytic converter). If there is a plugged exhaust, you should be able to open the throttle up and watch the vacuum drop due to the increased back-pressure in the exhaust. I believe EricTheCar Guy also mentioned taking temperature readings at the front and rear of the converter for additional information as well.

                            The vacuum test is pretty straight forward and easy to perform. Keep us posted.

                            #435282
                            EricTheCarGuy 1EricTheCarGuy
                            Keymaster

                              Forget the sensors! Especially the TW if you don’t have a code. Don’t assume that it’s an electronic failure especially if you don’t have a check engine light. The computer is VERY good at picking up these faults so if it didn’t detect a fault with the TW you don’t have one. Check the basics, the entire time I’m reading your post I’m thinking timing, engine timing to be precise, make sure the engine is mechanically in time and that all your marks line up. Also check the ignition timing, if it’s not set using the proper procedure then it’s going to be off, here is a video.

                              http://www.youtube.com/watch?v=sGzxCCax … 9BA72160B1

                              I can’t stress enough how important it is to use the correct ignition parts on that engine, NGK or Nippon denso plugs only, NGK or OE wires only, you can go a little cheaper on the cap and rotor but OE is also best here. I’ve seen aftermarket PCV valves cause a condition similar to a vacuum leak, here’s a video on checking for those.

                              http://www.youtube.com/watch?v=9CPqbaSgcok

                              Here’s one on checking for voltage leaks

                              http://www.youtube.com/watch?v=x-U9WqJf … BD790DDA9C

                              The #1 rule in automechanics is KISS, Keep It Simple Stupid. Resist the temptation to go into the electronics and don’t forget about the basics as most performance problems are cause by the basics NOT the electronics.

                              #435283
                              CrUnChCrUnCh
                              Participant

                                Hey guys thanks for helping me try to solve this problem. I put away the DVOM as Eric suggested and watched the videos that he advised. I have watched these videos before but it doesn’t hurt to watch them again. I began by removing the number one spark plug after disconnecting the spark plug wires from the plugs. I then rotated the crankshaft manually counterclockwise until the number one piston was at top dead center. The first timing mark on the crankshaft pulley was lined up with the timing pointer on the lower timing cover. Then I removed the valve cover to expose the camshafts. I looked at the exhaust and intake camshafts and both were lined up. The timing mark on the intake cam was at the 9 o’clock position while the timimg mark on the exhaust cam was at the 3 o’clock position and the word up was at the 12 o’clock position on both cams. I then reinstalled the valve cover. I removed the remaining three plugs and checked the condition of all the plugs. The plugs were Nippon Denso Q20PR-U 11. The tips of the plugs were a greyish tan color and did not look worn. I checked the gaps and they were still at .040. I applied a bit of anti-sieze to the threads of each plug before reinstalling them and torqued each one to 13 foot pounds. Then I reconnected the spark plug wires. I then removed the positive crankcase ventilation valve and inspected it for any cracks. This PCV is an aftermarket one. I applied air to one side of the valve while holding my thumb on the other side and could not find any leaks. I reversed the valve and performed this test again but still could not find any leaks. I shook the valve to see if it would rattle freely and it did so I reinstalled the valve. I started the engine and let it warm to normal operating temperature. Then I connected a tachometer to the blue wire from the distributor and used a paper clip to jumper the service connector wires located under the passenger side of the dash. According to the tach the engine was rotating at 750 RPM. I used the timing light to check the timing marks on the crankshaft pulley. The timing was within specification at 16 degrees before top dead center. Then I disconnected the timing light and the tachometer. I then removed the hose for the PCV valve at the intake and connected a vacuum gauge. The gauge read 22 inches of vacuum with a steady needle. As I opened the throttle plate the needle would dip slightly and rebound back to 22 inches of vacuum. I turned the car off and disconnected the vacuum gauge. I waited until dark to check the spark plug wires for arcing. I started the engine and let it idle while I sprayed the plug wires with a spray bottle filled with water until the wires and distributor cap were dripping wet. I didn’t find any signs of arcing. To answer the question asked. If I am able to get past the stumble and not let the car stall the car accelerates smoothly and has plenty of power even climbing hills. What should I check next?

                                #435284
                                MattMatt
                                Participant

                                  And still no codes? I would personally look at the EGR system next. From Eric’s videos, Hondas seem prone to these issues. Wish I was there in person tho. I could be way off though. Just thinking out loud.

                                  #435287
                                  dreamer2355dreamer2355
                                  Participant

                                    Does it want to stall in all gears with it being a manual trans?

                                    I would be looking at a possible clutch issue. I would check the cluctch free play and the linkage/hydraulics to make sure everything is adjust correctly. It could be that your pressure plate is not releasing fully.

                                  Viewing 15 replies - 1 through 15 (of 19 total)
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