When it cuts out, is is only while carrying power/accelerating. Not necessarily wide open.
I have experienced similar occurrences with bad spark plug wires or a broken spark plug in other cars.
Two new ignition coils and it’s still surging once hot, under power. I have a new thermistor sensor I’m going to install and see if that helps. Any other theories out there?
My mechanic said that the thermister was 200ohms off of the above chart when hot. Would that be enough to throw the timing off?
I wouldn't think so, but they don't give any explanation of how it should work when everything is at spec nor what would happen if it's giving an incorrect reading. Also, I think it would be a different effect if things were tweaked up when everything is correct and the "when hot" resistance suddenly increased by 200 Ohms vs if things were tweaked up when the "when hot" resistance was already 200 Ohms too high. My guess is the main function of the Thermister is to tell the ECUs to add some more enrichment during open-loop operation (by increasing the constant EHA current of open-loop operation) if the coolant is cold. (During closed-loop operation, the EHA currents would be set by the O2 sensor signals unless the WOT switch is closed.) But I have no evidence for this so do let us know if your fresh Thermister makes an operational difference (and your fresh Thermister might necessitate a warm idle mixture tweak if the last warm idle mixture tweak was done with the erroneous Thermister resistance) . When you say "Two new ignition coils..." does that means new coils and new power modules or just new coils?
I tried two new complete coil packs.They had the power modules included. Next I’m going to try new distributor caps and rotors. My mechanic seems to think it’s in the ignition. I guess I’ll try spark plug cables last.
A little surprised that you would buy new coils and power modules before inspecting the caps/rotors/buttons/extenders and measuring the wire resistances (and repiercing, if necessary), but still wishing you positive mojo.
I would not be willy-nilly changing parts without testing them. Is your mechanic doing this or are you? If it's your mechanic, he/she is not a very good diagnostician and you will be spending unnecessarily until you find the problem. Spend your money on finding the problem, the fix is the easy part generally. Good luck.
Honestly, I felt like it needed new rotors, caps, new extenders and wires anyway. I just hoped it would solve this weird issue. It still does it. Observation: *It cold starts and hot starts perfectly fine and seems to idle without trouble *Even when its hot, if the car sets for a few minutes running and then load it it doesn't do it for a minute of load *I can not get the two manifolds to balance vacuum while trying to set the idle *When it starts to miss under load, it feels like someone is turning a switch, controlling this missing, on and off. As soon as I relive pressure on the gas pedal the missing stops
Thanks for the response. I do have a workshop manual but it is for a car with warm up regulators and mine does not have them. I will try running it without the O2 sensor today. I have a K-jet fuel pressure tester. Can you show me which port to test? Just for a backstory: I had a mouse eat part of the wire harness next to the starter. The tach gage did not work as a result. I was able to splice the wires and got the tach up and working again. I dont think there was ancillary damage but dont know This problem started prior to the belt service. The boot, under the manifold, and on top of the throttle body had disintegrated and I thought that was the reason I was getting a miss-balance in the manifolds. I figured they were going to have the assembly apart. After the service, the shop I had the car in was raping me on diagnostics so I brought the car home.
Question?? one thing that I have noticed: on the drivers side throttle body, the bypass screw has almost no tension on it. The other side has much more resistance. Is that normal?? Could there be an O-ring missing?? Cant find a diagram of the throttle body
I don't like that statement at all (as getting things balanced at idle is the prerequisite for worrying about runability). Even though you say that the problem started before the major service, you can check the rough alignment of the cams by setting the crankshaft to PM1-6 and #1 firing (i.e., TDC for #1, and #1 and the end of its compression stroke) and comparing the secondary marks on the cams to the marks on the plastic timing belt covers. These marks aren't very accurate, but they should tell you if something is way off (like a whole tooth): Image Unavailable, Please Login I prefer to use the port where the cold start injector is connected -- as my kit had that thread size fitting (and it should still start-up without the cold start injector connected on one bank), but either port is OK: Image Unavailable, Please Login This link should get you pages D61-D106 of the TR WSM that covers US TR KE-Jet with Lambda: https://www.dropbox.com/s/18bidr3sgbofytb/Workshop%20Manual%20Testarossa%20Supplement%20Catalytic%20Converter%20D61-D106.pdf?dl=0
The air bypass screws should only be opened by something like 1/2~1 turn from fully closed. If they are opened multiple turns = not good. There is an o-ring under the washer (with the downward curved outer lip) that the coil spring under the head of the air bypass screw presses on. It's meant to seal the threads of the air bypass screw. (Mine were rock hard so I replaced them.)
When the air bleed screw is removed there is a spring, a cup shaped washer and the o ring fits in the recess of the cup shaped washer. They should stay together as a unit when removed.
Ran home for lunch and did a couple of experiments. While hot and running, I pushed down on each of the flaps on the fuel-air meter. The drivers side lost some RPM but kept running, I pushed the passenger side and it immediately died. Went to the electrical bay and pulled the relays and had the same results. I jumped the fuel pump relay and the pump came on. When I pushed down the meter flap I could hear the injectors sing. While running, the drivers side manifold is at 16.5 PSI and the passenger side is 12 psi. I will check the fuel pressure check when I get home this afternoon
So I’ve identified the fact that the issue is in the driver side. I hooked a timing light up and all of the cylinders are getting spark. That being said, the vacuum pressure is 5 pounds more on the driver side than it is on the passenger side. One thing that I did notice however, while at idle the driver side fuel or meter flap is closed completely while the passengers is open probably 2 mm. Here’s the question, it’s got to be an issue with either the throttlebody not allowing the vacuum pressure to get to the meter and suck the flap down or the mixture.I could try to adjust the mixture so the flap clearance is visually the same. Thoughts?
Are you sure about those units? Those values would more typically be 16.5 in. Hg (inches of Mercury) vacuum and 12 in. Hg vacuum (not psi) if measuring the intake manifold vacuum.
Definitely not good -- the airflow metering flaps should be deflected about the same amount open at idle (maybe 1~1.5 mm). Are you sure the fuel distributor plungers are moving freely and easily? The way to test is (key off, engine not running) break open a fuel line connection (like at the cold start injectors) to make the fuel pressures zero (be careful, fuel will squirt out so wrap with a rag as you loosen). Then deflect the airflow metering plate down with a finger -- they should move easily, feel the same, and return easily to the rest position. If they are OK, then either you have a huge air leak somewhere or your throttle plate and/or air bypass adjustments are extremely different on the two banks.
Both seem to have the same back pressure. When I jump the fuel pump I can hear the injectors singing so I know they’re getting fuel. The strange thing to me is there’s higher pressure on the Driver side however the flap is properly open on the passenger side and not on the driver side. That tells me it’s either mixture setting or throttlebody setting. Am I right??
This is a measurement made when the plunger is working against the full fuel pressure (so any drag/resistance in the plunger motion is hard to detect) -- far better to make this comparison of plunger motions at zero fuel pressure. Yes, if the Driver's plunger motion is OK (i.e., it moves easily a zero fuel pressure), having a high vacuum in the Driver's intake manifold, but little deflection of the Driver's airflow metering plate would indicate that the throttle plate and/or air bypass screw is/are too much closed.
Were the crank position sensors disturbed at the flywheel? Both fuel filters replaced? I have suffered a similar symptom in the past (more like a misfire when the engine dropped #8 as the crank position sensor lost signal). It does sound like you are on to something with the driver's side fuel metering unit.
It’s looking like a fuel delivery issue. Someone put the wrong relay on the driver side fuel pump relay. Still a little suspect of the tachometric relay. That will be tomorrow’s project
