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I have an Acura tl 2003 type SI noticed some hesitation when I'd park my car and the RPMs dropped sometimes as low as 900. Now today I made a poor decision to put some injector cleaner in my tank, started the car and Shakey shake engine lights coming on. I have a scanner I put it on and these misfire codes appear. p1399 p0300 p0304 p0301
It could be coincidence that the Seafoam injector cleaner was used and this problem appeared.
I did check my EKG ports and cleaned those on the top of the engine under the plate the issue still exists. I let it idle for two hours thinking maybe the injectors would clean themselves. Nada.
I ordered some new injectors, O2 sensors and a MAP sensor.
Wow, you went whole hog right away. First the idle in park should be about 750 (+/- 50) RPMs. The second issue Seafoam. I would assume that the Seafoam is causing the issue and still in the system. I am not sure you need to replace anything yet. I would keep trying to run after I cleaned the items you ordered for replacement.
I purchased Bosch O2 sensors up and down stream they aren't installed yet.
Further information: I disconnected each cylinder while running, and they all had an effect except cylinder 1. I did a voltage check with my multimeter, and I'm only getting 2.5V on the harness on cylinder 1. Not sure where to go from there. The fuses look good, it doesn't look corroded inside the plug, and these wire harness aren't plug and play it looks like they are spliced into a main wire. Any advice?
I mean manufacturer spliced into the main harness like below. Is each individual ignition coil wire spliced into a main wire feeding each of the individual connectors, or is ran from a central location? because like I said the other connector wires are receiving 12v+ but cylinder one is only receiving 2.5 to 2.8v, I checked for corrosion and even pulled out the wires from inside the connector to check if it was seated incorrectly. It's definitely up the line from the connector.
Ok. Standard wire harness. Below is the schematic. I assume the voltage was measured at the connector when it was not plugged into the coil. If it was plugged in then the coil could be the problem. Ifthe voltage was measured when it wasn't plugged in it does look like you need to open up the harness to find the issue. Do you have a copy of the service manual? (https://www.dropbox.com/s/alzlpd489p...ANUAL.pdf?dl=0) it is a large file someone posted this a while back and I am reposting the link.
General Schematic -Injectors are powered through the main relay
I purchased Bosch O2 sensors up and down stream they aren't installed yet.
Take those Bosh's back and get your money refunded.
If current O2's are original, at 195K, & you go the extra length to replace them, your J32A2 engine would prefer Denso upstream #2344727 & Denso downstream #2344621.
RockAuto has good pricing on these & a 5% discount coupon.
Okay those diagrams you posted weren't helpful because it doesn't show the ignition coils but I was able to find the wiring diagram I needed. I highlighted the wiring path for cylinder ignition coil one. It looks like it does splice into a main wire that powers the 12V lead to the coil. I might be wrong? Considering the other leads from the harness are providing the correct voltage, it leads me to consider that the segment I highlighted in orange has a break in the wire or damage to that specific lead. Is my reasoning sound?
Sorry about the wrong diagrams; I had fuel injectors on my mind since you used the Seafoam. Did you measure the voltage with the coil connector on or off? The reason I ask is if the coil has a problem the voltage can be lower (if the coil is connected to the harness).
Coil is disconnected, yeah that's a legit question and I should have stated that. It's okay I appreciated the help even if the diagrams were incorrect, atleast you gave me the tools to find them myself. I also noticed on my diagram that the electrical 12v wire is not the orange highlighted wire. The 12v power source wire goes to F on that diagram, regardless it does look like a lead off the main line so it should be repairable right instead of having to trace to the power source?
Since the coil is disconnected I think you are correct and need to start working your way back to find out where the wire is has a problem. There is one or two more tests you can do before opening the harness. First the voltage going to the coils should be pulsed when it is firing. A digital volt meter is not the best to measure this as the pulses have to be captured at the right time to measure it correctly. If you have an analog meter (one with a needle) it will give you a better reading, the needle will jump around. If you don't and you want to be sure it is the wiring you should swap the coil and plug from a nearby cylinder and see if the issue remains with the one cylinder or follows the coil and plug. If the problem remains with the one cylinder then it's harness time. If not then its the plug or coil.
I did see the voltage jump around between 12 and 13.8v so it must be working correctly on the other leads. I hope the harness is easy to fix this is kinda scary considering it could need an entire new harness, let's hope not. I'll try swapping the coils to satisfy my curiousity and report back. thanks.
Wiring is easy to repair with a few good tools and techniques. It is a pain if a connector is a problem but that can usually be worked around unless you want the original connector/look. I can help you there if needed. Look to see if the wire is pinched or stretched. Check connector connections for corrosion and give it a mild pull test for that wire. Use a sharp probe to go through the covering with as minimal damage as possible while working along the wire. I would check first to make sure signal is coming off the computer and the ground is connected well. I think the manual has the connector and pins for each of the signal lines.
How do you make sure the signal is coming from the computer? Is there a voltage from the communication wire I can measure or ohms? I didn't notice anything on the communication wire when I put the multi meter on it.
Measuring from the signal wire to ground should show pulses (only when the car is running. Use care not to bend the PCM connector pins with the probe. Found the diagram for the connector, see below. See notes in the section Also, go to section 11. Look at page 120 (11-120) and on, it has troubleshoot procedures.
Swapped coils, the problem followed the coil. Still what I find weird is the voltage drop from that plug. I'm on my way to buy a new coil so I'll check the voltage again when I get home. Im kinda glad it's not wiring issue, when I was looking at the harness each lead is individually routed to a main plug it would have been highly painful to restring the individual wires and rewrap the harness.
Ok. Not too surprising. It is hard to capture pulsed signals on a digital volt meter (DVM). An O'scope is best, analog meter is better than a DVM. In any case do not be too surprised if other coils start to go bad. The SMP coils from Rock Auto seem to work Ok. Six would cost you about $155. I would replace the one coil but be prepared to replace more in the future.
Unwrapping and tracing wires is a pain. A lot of cleaning to rewrap properly but sometimes it just is what it is, undressed wires are easier to see any damage. Let us know what happens with the coil and then we can look at your RPM's as your original post has them way too high. You must be going through a lot of gas.
The new coil fixed the misfiring. I am still having issues with low rpm. It idles at 750 I think my original 1200 was way off. Sometimes it goes to 500 and I feel like my car shutters a bit. Perhaps it is the O2 sensors or something? I ordered a new MAP sensor for like 15 bucks. I am going to replace all my coils they are already ordered, Denso brand. I returned the Bosch O2 sensors, when I have cash I'll buy the Denso ones. Maybe it's another coil going bad
Great. Since the idle drops to 500 do you have an OBDII reader? If so are there any codes? If you don't have a reader I highly recommend that you get one. They are pretty cheap these days.
You should look in the manual and read about the Idle Air Control Valve. It is mounted on the underside of the throttle body. I hope you are not developing an issue with it but it just may need to be cleaned out. This is one of those parts I think you should buy OEM and it is expensive. If you are going to try and clean it out you will need to get a new throttle body gasket and a new Idle air control valve gasket. Before you do you should make sure you are using good gas (91 octane) etc. The IACV is one part you don't want to cause problems with so be gentle if you ar going to see if it needs cleaned. There is usually a code that it generates when it is bad.
You can clean out the throttle body and the EGR passageways in the upper intake manifold.
Okay the problem returned. The voltage must be dropping on cylinder one coil. That's probably why it eventually failed. This is disappointing now I need to figure out if it's a ground issue or what. Any suggestions would be appreciated.
I haven't fully investigated everything yet but I did notice the problem is appearing when I have my heater running, maybe the heater core is causing an issue. I gotta crawl under the passenger side and check stuff out here soon.
You will need to bleed the air in the engine coolant. If you heater core has air in it then when it is turned on and the air/coolant circulates air bubbles get stuck and the idle goes bad. You need to "burp" the car. Basically fill the radiator. Use a funnel like the picture below poor in some coolant so it is visible in the funnel, and let the car idle, gently squeeze the radiator hoses to help get the air bubbles out. Turn on your heater to allow flow through. There is a written procedure somewhere. Try searching the threads.
I used the wrong term, I meant the blower motor might be causing an overheating I did smell a burning, and I did replace this once before I will need to take a look. Perhaps that is causing a voltage issue, I know the blower motor resistor and plug often overheat and melt, it's happen before and a known issue with these vehicles. Can a resistor cause a whole system voltage drop? The motor shuttering goes away when my heating and blower is off, this could be completely coincidence.
I used the wrong term, I meant the blower motor might be causing an overheating I did smell a burning, and I did replace this once before I will need to take a look. Perhaps that is causing a voltage issue, I know the blower motor resistor and plug often overheat and melt, it's happen before and a known issue with these vehicles. Can a resistor cause a whole system voltage drop? The motor shuttering goes away when my heating and blower is off, this could be completely coincidence.
Sorry if I missed it, but have you ruled out the AC compressor? In cars with auto HVAC, they can run the compressor to keep humidity down even if you haven't selected "AC". An AC compressor is way more likely to stumble an engine than electrical load IME...BTW a low idle may produce slight dimming of lights, which may lead to thinking it's an excessive load, when it's actually the alternator dropping off at low revs
Ok, though by turning on the heat it will allow the coolant flow. Several possibilities have been mentioned. First any resistor will cause a voltage drop, that is their purpose. They have a voltage drop across them and current through them. In the past the blower motors had some kind of service notice on them to rewire a connector and replace a wire with a heavier one (if I remember correctly). One thing to try is disconnect the power connector from the blower and turn on the heat and check the idle. Also, as JuicyJ mentioned then turn the temp so the AC comes on and check the idle. By checking both with the blower disconnected you can tell if the additional load on the engine is bogging down the alternator. Monitor the voltage at the battery when doing each of the above. It should be around 13.4 to 13.7 Vdc when the alternator is working. After checking the above reconnect the blower motor and repeat. If the car idles normally without the blower motor connected then gets bad when it is connected. the blower motor is shorting out, drawing too much current, and the voltage to drop.
If you need to check the alternator further I do the old fashioned test of starting the car and removing the battery cable. If the car stalls, the alternator is bad or going bad. Measure the voltage at the battery cables.
One warning if you see burning/melting at the blower motor connector, clean off the connectors before you try anything with power through that connector. Watch for smoldering/fire. Replace the connectors that are damaged. In some of the old threads there should some about the blower motor advisory.
03-03-2023, 07:53 PM
