Integra No Start

Zachary Mobile Technician Austin, Texas Posted   Latest  
Question
Driveability
1993 Acura Integra LS 1.8L (B18A1) 5-spd (YS1)
Crank / No Start

VIN: JH4DA9351PS024878

Hello everyone. Thanks as always for taking the time to read this. Customer purchased this vehicle recently and it has some "mods" to say the least. It's my understanding that it's essentially still a B18 engine but is an Si head and a GSR block. That being said, the factory wiring and related seems to mostly be intact. He said it ran great the day he got it and then died on him. Customer replaced the ignition coil with an Autozone unit with no change. When I got to it, the first thing I did was check for spark of which there was none. I can smell fuel during and after cranking so I decided to focus on the spark for the time being. Engine cranking was very slow and I assumed the battery was low due to attempts at trying to get it started. At some point, this battery was relocated to the trunk/hatch area and poorly I might add. I hooked up my service truck to boost the battery for initial testing. After verifying good power feed to the igniter & coil, I took a scope capture of the ignition trigger signal to the igniter from the ECM while attempting to crank. As you can see in that 1st picture, the signal never pulls all the way to ground. My understanding of this system is that the igniter outputs a 9-12V signal and when the ECM has all the right inputs during cranking, it simply pulls the signal to ground. Based on this and the battery relocation, I suspected a ground supply issue to the ecm. I charged the weak battery and proceeded to check ECM power and grounds. According to the wiring diagrams I found in Identifix, there are two grounds and one power feed. This seemed odd to me as I would've expected at least one more power but that's all I saw. I took the 2nd scope capture during another cranking event. The two ground traces mirror each other here which is why you may not see the blue one. In any case, the grounds to the ECM stay above 1.5 Volts while cranking. I used my jumper cables to run a temporary ground from battery to the engine. The cranking speed increased dramatically and the signals changed accordingly as you can see in the 3rd capture. Both the ECM grounds and the low pull of the trigger signal stayed closer to 350-400 mV. Still a little higher than I'd like but much closer to the truth. When I rechecked coil dwell, I got what you see in the 4th capture. According to Identifix, the coil dwell should mirror the trigger signal which makes sense based on other systems I've seen. Even with the temporary ground repair, the coil negative never gets pulled all the way to ground. I don't particularly like that the high end of both the dwell and the trigger signal are below the 9 volt threshold but perhaps that's normal for this system. Been awhile since I've got this deep on an older Honda and I don't believe I ever took these kind of scope captures. My thought is the igniter has failed. Wouldn't be a surprise on one of these and the internal condition of the distributor is pretty rough. I went ahead and reinstalled the original coil just to be safe as it wouldn't be the first Autozone part that's junk out of the box. That said I didn't expect a change based on the dwell signal. As usual I've written a novel here but I always hate to leave out anything that might be important. I appreciate any and all feedback for this and hope everyone has had a great week. 

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Bob Instructor
Phoenix, Arizona
Bob Default
 

Historically those engines had distributor issues. There really isn't much to those systems. Since you fixed the ground issues, if I had to throw a part at it, I'd say the igniter module. We used to replace the whole distributor assembly. That way you get a replacement coil, pickup coil and igniter. With new shaft bushings and seals, which were also problematic.

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Zachary Mobile Technician
Austin, Texas
Zachary Default
 

Bob, That was my thought as well but I wanted to be sure I wasn't missing anything. This one will definitely get the whole distributor as the wiring inside of it looks awful and has insulation peeling off. Thanks for your input.

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Luis Technician
Lake Forest, California
Luis Default
 

We NEVER replace the whole distributor unless is factory Genuine part ALL aftermarket distributors are junk. Is this a JDM swap. Did you verify block is B18C from a GSR and if it has a Si head is from a B16 which is fully interchangeable, what about ECU is it a JDM ecu or original? If JDM ecu normally it has a jumper harness to work with US. I would not rely on factory wiring diagram more of a…

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Zachary Mobile Technician
Austin, Texas
Zachary Default
 

Luis, No luck with any of the aftermarket distributors huh? That's a shame though not a surprise. It's not a JDM swap as far as I know. Haven't gone so far as to verify the block and head, just going off of what the customer told me. I wasn't sure if that would be necessary to verify that going into this so I decided to approach it as if things were stock until I had a reason not to. The ECU…

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Luis Technician
Lake Forest, California
Luis Default
 

Are you able to pull dtc codes by jumping the scs connector under the glove box.. Ecu driver may be fried. Try a known good ecu those ecu are easy to find and affordable P28 ecu, honda tech forum and eBay. tripple check the ground at thermostat housing

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Zachary Mobile Technician
Austin, Texas
Zachary Default
 

Luis, I looked for the connector but didn't see it. It's typically blue with 2 wires correct? I can double check when I get back out there. If the driver was fried wouldn't you expect it to not be able to pull the signal low?

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Dmitriy Analyst
Toronto, Ontario
Dmitriy Default
 

Where does the power for the coil come from, according to the wiring diagram and/or the visual inspection? Is there is a voltage drop somewhere upstream, just like you had with the grounds? (Which happens only when the starter is working) Oh, and are battery terminals clean and tight?

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Ray Diagnostician
North York, Ontario
Ray Default
 

This capture is from a 98 Accord 2.3 from cranking to start. CH A is the TDC sensor from -2.5v to +3v CH B is the CKP sensor from -2.3v to +3.2v CH C is the CMP sensor from -3v to +2.9v CH D is the ign input signal and the ground is at 0v cranking, up to 11v

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Zachary Mobile Technician
Austin, Texas
Zachary Default
 

Ray, Thanks for sharing this. I'm going to double check voltage drop across the ignition switch and the circuit that supplies it as it seems the amplitude of that trigger signal should be higher than what I'm seeing.

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Zachary Mobile Technician
Austin, Texas
Zachary Default
   

Dmitriy, The power for both the coil and the igniter come from the ignition switch through the under dash fuse/relay box according to the factory wiring diagram. I've no reason to believe this has changed as the wire color matches up. I did check voltage out of the ignition switch on this circuit while cranking, but it occurs to me as I read your response that I didn't check voltage drop across…

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Ray Diagnostician
North York, Ontario
Ray Default
 

Check the power and ground to the coil and to the igniter by loading the circuits with a headlight. The headlight draws 4 amps across a battery. Measure for the 4 amps, even if the headlight lights up when connected to the coil and to the igniter. The power and or ground circuits may only be able to handle 2 or 3 amps to the headlight.

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Zachary Mobile Technician
Austin, Texas
Zachary Default
 

Ray, That's an excellent point and I should've done that already. I'll include that check in my follow up when I get back to the vehicle shortly. Thanks so much for taking the time to respond.

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