White95Legacy

Nah, they sold the car after something else broke that they didn't understand, so they bought a minivan. I didn't check to see what the new problem was. My guess is the old problem was something in the wiring harness like ABS computer, or cruise control, or some other module was sending bullshit signals to the ECU to cause the ECU to cut fuel pulses. Or it might of been a sensor on the engine side. I kept telling him to replace the 16 pin engine-chassis connector with a new connector, in order to bypass the corroded and questionable connector problem, but he didn't want to do the work.

The Main Relay is a double pole single throw switch, I probed both poles on the switched side and it stayed right at 14v while the car was driving and the hesitation was occurring, I had the meter right there on the seat next to me while driving and engine was hesitating/delivering no torque. So why would I replace a relay that is working fine? I had a good reason to believe it was the ECU, the injector pulses were going almost non-existent when the short term fuel trim reading was in the positive. It does this with or without the MAF. The ECU is a complicated device that is impossible to probe for every possible problem internally, but a relay can be probed. So you are saying the ECU will occasionally cause the lean condition by cutting it's fuel pulses short when the MAF is not hooked up? Or is hooked up but is malfunctioning? Something else is shorting or confusing the ECU.

Because it does the same exact thing if the MAF is disconnected entirely. And when the MAF is hooked up it reads grams per second just fine on the scanner graphs. Without the MAF the ECU is going according to TPS and O2 sensors and it still has the loss of power like something is loose. Was only $30 for the ECU, now they can eBay the new one.

Grrrrrr, was not the ECU. We put a different ECU in and same exact hesitation/total loss of power. This is why I used to be a mechanic, but now I ride a 20lb road bicycle with a powermeter 10,000 miles a year. Lot less to go wrong with a bike, and I can brag about how my wattage output gets better every month. Has a rear rack that measures 40cm x 65cm and can carry 70lbs. Can average 14 mph without getting sweaty, 20+mph if I wanna get somewhere fast. Think were gonna tear the wiring apart and check everything, gonna tell my friend to google for some new wiring harnesses. First we should check all the grounds, not just the grounds that are easy to reach. I hope we don't need to tear the dash apart to find the ghosts. Does anyone think it could be a connection to the crank/cam position sensor? There was no data for those sensors in the ScanMaster-ELM software I was using. I know it's a 20 year old car that some would say get rid of, but we're still having fun digging deep into the engineering behind it. Thanks all.

I told them to buy dielectric grease a year ago for other projects, now their solar system has terminal corrosion, maybe electrical problems in the future will teach them to diagnose problems and find solutions, but they will probably just think god broke it. Thank you

It might not have run perfect, but after a few minutes of driving with MAF unplugged it lost power for a few seconds, more than once, same hesitation problem the car has had since they bought it. We didn't test the performance too much, but it idled ok, seemed fine. We tried the same with the TPS, unplugged it and drove around, that too made almost no difference in performance, car drove ok, but still lost power/hesitated occasionally, more than once. We tried unplugging both the MAF and TPS and the car refused to start, but unplugging just one of the two allowed it to still be driveable, but didn't isolate our problem.

I just tested the injector 12v from the relay, I probed the yellow wire right by the injector and ran the wire inside the car, started the car and it read 14v, drove for a while and had a hesitation for a good 5 seconds of total power loss and the voltage stayed at 14v. So it is not a fuel injector positive supply issue. The injectors ground is switched by the ECU. We took apart the ECU and everything looks fine inside, no cracked solder joints, no cracked board, no burned components, no severed terminals. But one of the components could be worn out internally, maybe a switching controller for the injectors. We were browsing ebay for ECU's and they are only $30-$50 used, numbers match up, so he is ordering one.

We were driving around the neighborhood a few weeks ago, I pulled over, disconnected the MAF, started up the car and it drove ok, but the hesitation still happened occasionally without the MAF even being connected. Car drove exactly the same without the MAF, hesitation/total loss of power was just as often.

I should probably tag along when my friends family goes on a long drive and play with all the features of this software to see if any abnormalities are happening in unexpected places.

We'll as long as that was not a hesitation at 142 seconds, which I don't remember if it did, but I don't think it did, that would prove that a lean mixture can make the O2 sensors read 0.0 volts. I think the O2 sensors just use the 12v from the relay for their heater, and the sensor elements generate a voltage which the ECU reads. I guess I should probe the O2 sensor leads for voltage to see what the 2 wires going to the ECU are doing to see if I am wrong about that theory. So the fuel pulses go really short during a hesitation causing a lean condition, the O2 sensors read 0 volts (wikipedia said a heated O2 sensor would read 0.2 volts during a lean condition, I guess if it is very lean it could read 0.0 Volts?), the MAF and TPS keep reading just fine otherwise the ECU would not be reporting that to my laptop, the ECU recognizes the lean by reading it's O2 sensors and is trying to adjust it's fuel trim to +25%, but the injector pulses go short. I'm starting to think the ECU has a damaged circuit internally, something to do with the injector drivers. Maybe I can convince my friend to buy an original ECU from a junkyard or ebay, we could install it and see if it fixes the problem, if it doesn't fix the problem we reinstall the old ECU and sell or return the one we bought. We can check if the ECU can be taken apart and then I can carefully look for damage. Another idea is one of the hundred wires going to the ECU is getting shorted or overloaded or crossed with another data wire and causing the ECU to act stupid. On the other hand I never did check to see if the 12v from relay to injector circuit is staying on, maybe the short fragments of pulses I see on the oscilloscope is just interference from something else and not injector pulses at all. On the other hand the MAF is working fine and it gets 12v from the same power relay circuit as the injectors and the ECU switches the individual injector grounds to pulse them, and since the car still had the same hesitation with the MAF disconnected I assumed the injector/MAF 12v from relay was fine. And here in the scanner reading we see the MAF working fine so I still doubt the injector 12v is turning off.

Nope, too expensive for my friend, taking a more diagnostic approach.

Here is a photo of my screen during a hesitation that happened between 165 and 172 seconds, right where the oxygen sensor voltages drop to zero, engine rpm spiked from 1200rpm at 172sec to 2700rpm at 173sec, I didn't downshift to boost the rpm, so power came back around 172sec.

Got the OBDII Bluetooth wireless code reader. Paired it with my laptop and displayed a bunch of graphs on my screen while driving. When the hesitation occurred throttle position worked fine, grams per second of air kept reading fine, but both front and rear oxygen sensor voltage dropped to 0. We will probably inspect the oxygen sensor wires real good. Probe them to see if they are getting shorted out or a wire is disconnecting. Inspect main relay connector B47 wiring since it supplies both oxygen sensors with 12v.

I worked on an EJ22 recently, but this was 2 weeks ago I'm trying to remember from. Here's what I did wrong, luckily I didn't damage the valves, but could someone tell me why the manual says Intake valve opens 1 degree BTDC when in fact it does not, and exhaust closes 12 ATDC when it does not. Here's why I think it's wrong, or I'm wrong or idk. We had the engine out of the car for clutch and head gaskets, we just finished the head gaskets and it was time for the timing belt to be installed, intake and exhaust manifolds were not installed yet so I could see the valves, spark plugs were removed too so I could see the pistons. The service manual said intake valve opens 1 degree BTDC, so I brought a piston to TDC and I set the camshaft so the intake valve was just barely open, the manual said exhaust close 12 degrees ATDC and the exhaust valve was open a little more then the intake, seemed perfect. So I put the timing belt on, then I rotated the crank and checked each cylinder one by one to make sure I had it right. So I brought the cylinders to TDC between the exhaust and intake strokes then I rotated the crank 1 degree backward and the intake valve closed, then I brought it back to TDC, then I went 12 degrees forward and the exhaust valve just finished closing. Seemed perfect and by the book. The little marks on the cam pulleys lined up with the marks on the covers, but the dash on the crank position sensor wheel didn't line up with the mark where the crank sensor was. Before I tried to install the belt I checked to see if it was an interference engine by opening the valves all the way and gently bringing a piston to TDC by bare hand and there was no feel of collision, but that doesn't mean the lash adjusters were at their running height when filled with oil, and at high rpm some valve lash or piston lash wont bend the valves, so idk if this is an interference engine or not. So I thought I was right, we put the engine in the car and we tested it before we put the radiator back in, and the car had trouble starting, the valves sounded like their timings were off. So we took off the belt and lined up the small dashes on the cam pulleys with the marks on the covers, and lined the crank sensor wheel mark up with the mark by the sensor. Car started fine and it drives fine. But the valves open and close at way different times then it says in the book. I had to release the timing belt tension and rotate the crank a few degrees to line up it's mark, it wasn't off by much, crank was off by 3 belt notches if I remember correctly, Crank pulley had 24 teeth, cams had 48, not enough mis-timing to damage the valves and it didn't seem like an interference engine. We didn't mess with the lash adjusters but with spring tension sitting on them when the engine is not running they bottom out I think. Can someone explain why it says intake opening 1 degree BTDC, exhaust closing 12 ATDC, and when I put the belt on the correct way they open and close way different?

We cleaned the 16 pin connector again and it still hesitated a few times while we were driving today, not nearly as much hesitation the first day we drove it after putting the engine back in before we cleaned the 16 pin connector. I had the oscilloscope running and the fuel pulses cut short during the hesitation, ignition pulses kept sparking away like they were supposed to. I noticed there were 2 switches on the clutch pedal and not just 1 like I would have assumed. Sometimes the starter motor seems to not want to start unless the clutch is released and then pressed again, then earlier it refused to start after releasing and re-pressing the clutch 4 times, eventually we push started it since we were parked on a hill. Since then it has started fine. Might be an engine ground. We could also try bypassing all 16 pins of the connector with jumpers as a test to eliminate that connector as the problem, but that would involve alot of jumpers and risk shorting something out, or taking the female connector apart and scrubbing the female pins and making sure each one has decent friction when inserted onto the male pin. The OBDII scanner should be here next week hopefully.