Its a god test though test drive with O2 unplugged
Like 5 minutes or like 30? I image it takes 4-10 minutes to go from open loop to closed loop. If it's a longer period, that points to something thats prone to heat soak. Electrical components. Anything mechanical would present it self all the time imo.
breaking up at rpm yeah crank sensor Fuel trims, crank sensor also if thats the RPM issue TB's absolutely suck after 25 years. I rebuilt 2 sets and car felt like new. With play and air gaps was hard to hold a metered flow. Smokey test those suckers while your playing. I have the 12 chanell mercury tubes I use to tune them if you need them
SoCal1 Tim. I did a smoke test on the intake (and exhaust) and no such leaks were found. Tight as a drum on the intake side. Slight leak on the exhaust side. Big update today. 1) we are taking the engine out because it has been more than 5 years since the major service (which I did on this car) and it is showing major signs of due time again. a) oil leaks in several seals and gasket places b) broken cam shaft position sensor c) gearbox oil leak at the right side cover d) cappuccino color gear oil meaning the heat exchanger is done for e) water pump coolant leaks So instead of peace meal approach, it is coming out this weekend (Eff the 95F weather) I'll keep a running list of things I found and update this thread when I close the engine back up.
I just wanna say that I appreciate this write up cause it is a teaching tool for all of us that do our own work on our cars. I wish I could help, but I have no new ideas as to whats going on with your problem child. I can't wait to hear what fixes it. Best of luck Mitch. You are a great asset to F Chat members.
Before the engine is out, I wanted to add more diagnostic data so I made up this to-do list before engine out. Check combustion temperature for each cylinder at the exhaust Check ground points at the head Check crank sensor operations Check cam sensor operations Check throttle position sensor operation Check MAF operation and numbers 1) it turns out I am unable to do this because my Laser thermometer only goes up to 500F and it won't be good enough for this test. I need to get a new one. 2) Ground point checked out for this engine at rear of Bank 1 3) Crank sensor visually inspected OK. 4) Cam phase sensor, broken connector. See picture. 5) Throttle position sensor has one number out of six that is out of spec. Pin 1-3 resistance at Wide Open Throttle is 1.2 kohms, instead of 1.0Kohms maximum. This needs replacement 6) MAF air flow sensor read maximum at 3.5 volts, and needs to be higher than 4V see picture. I have always believed this car has multiple issues .... and so far it has not disappointed. This is added to the previously found issues: Loose number 6 injector clip. Bad one-way check valve on secondary air pump circuit, bank 1 Leaky exhaust gasket, bank 1 right before Pre-cat O2 sensor Disintegrating rubber bits inside fuel tank Image Unavailable, Please Login Image Unavailable, Please Login
I verified the crank sensor to be physically in tact, wires not messed up, and nothing is cracked. But we will change it anyway since it is 25 years old. I did not verify the cam sensor until just recently. The wires are intact but the connector is cracked badly and it can't be good. The MAF sensor thing needed a Digital Oscilloscope set up properly to capture the one time event of snap throttle closure which... happened today. And I am still scratching my head as to why Bank 2 is running rich and Bank 1 is running Lean as reflected by the LTFT. Also the rear O2 sensor is bouncing all over and that is just not right. I might put it back together with a set of borrowed original Cat converters to see if that makes a difference. Oh and added to the list: Loose number 6 injector clip. Bad one-way check valve on secondary air pump circuit, bank 1 Leaky exhaust gasket, bank 1 right before Pre-cat O2 sensor Disintegrating rubber bits inside fuel tank Broken Cam Phase Sensor Out of spec MAF sensor Cracked idle T-connector hose Cracked hose at secondary air pump connection to Bank 2
The resistance goes down with throttle application. 1.2 kohms doesn't sound like it's out of spec if 1Kohms is a maximum.
Just checked the manual and I see what you mean. I thought you meant that 1Kohms was the most extreme value allowed (from the no throttle value). Maybe I should change mine. It's even further out of tolerance than yours. Or could it be a cable/throttle body adjustment problem? My no and full throttle values are shifted in the same direction. What was your no throttle value? Folks, for reference, full throttle = 850 ohms +/-18%, no throttle is 2000ohms +/-20% On my Lotus, you could adjust the position of the sensor slightly. I recall someone trying this on a F355 by widening the holes on the mounts.
As far as the TPS yes you can tweak it as such I did mine this way as well, 348 yes but pretty sure it the same on 355's. https://www.ferrarichat.com/forum/threads/348-throttle-position-sensor-adjustment.453969/ Pretty much, a combination of issues as suspected. You'll get it for sure resolved. Problem is these cars tend to compile things, many things that make toxic pairs that is hard to diagnose as one item. Abbreviated list below that I did to avoid the situation you find your self in, you may want to consider some or all of these. Best of luck! crank sensors phase sensor MAF TPS FPR Fuel pumps Injectors Coils Ignition modules Every Check valve in the engine bay New vacuum lines and fittings Water temp sensors Oil Pressure sender O2 sensors Thermocouples Every light bulb in the entire car (dash included) Plug wires Plugs All new relays All new fuses Thermostat Fan temp switch Oil temp sensor Oil temp switch New radiator fans New ground wires and add 2-3 new ones
Eric, I am approaching half that list already. Likely to include all the ignition parts. By the way, what does replacing the Oil Pressure sender have to do with ignition, or your problem? This car does have a high pressure reading.
Absolutely nothing. While the patient is open and all that. It costs almost nothing to replace, your there, and avoids another fire drill later. My car has 0 problems and I mean 0. I'd hop in and drive it cross country and not give it another thought.
Crazy mitchel that all that stuff is broken since last 5yr service. My 550's suffer great underhood temps and when the 5yr comes it's like gee why am I messing with this perfect car? Anyway Bosch makes bad sesnors. I have had so many cam sensors just crack/disintegrate with the heat and fall apart in my had when removed that I just replaced them every 5 years. I use the kia 348 crank sensors and adapted it to the 550. They are so cheap I bought a dozen about 15 years ago. What a mistake! The bosch sensors fail all the time. To this day I have never had a kia crank sensor fail. I still have about 8 new ones left.
He's got after market unshielded headers on this car and all that heat is dumped right into the engine bay... cooking everything in the way. Remind me to check the engine mounts.
Next time engine is out I'd yank the headers then swain coat them inside and out, maybe wrap them too for looks.
So, the engine came out this weekend. The more I see, the less I want to see. Something has caked the entire front of the engine. Imagine an animal died and left its carcass behind. Water pump toasted. Idle valve T-hose cracked. Both knock sensors broken in pieces (this might explain a lot) Cam position sensor cracked. Power steering hoses (all) are leaking All oil hoses are leaking. Cappuccino color gear oil. So the list just kept growing. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
And now the list got a bit longer: Ignition related: Loose number 6 injector clip. Bad one-way check valve on secondary air pump circuit, bank 1 Leaky exhaust gasket, bank 1 right before Pre-cat O2 sensor Disintegrating rubber bits inside fuel tank Broken Cam Phase Sensor Out of spec MAF sensor Cracked idle T-connector hose Cracked hose at secondary air pump connection to Bank 2 Cracked TDC speed sensor (new today) Cracked, broken knock sensors (yesterday) Service related: Water pump toast Leaky oil lines (3 main ones) Leaky Power Steering lines (hi pressure and low pressure) Leaky heat exchanger Leaky gearbox side cover
I was going to say check or replace both water temperature sensors. They are cheap. I've seen a no CEL, garbage running, condition on a motor before and that was the problem.
More **** to dig up. This is the air-vent line for the fuel tank, and the secondary air pump (well, non-pump). Image Unavailable, Please Login Image Unavailable, Please Login
