Low idle/ dogging at cold start = When I start the F 355, sometimes it will seem like it is a low idle (900-1000) rpm as soon as the oil starts moving, which takes 3 full seconds for the oil pressure guage to move....then the cold idle seems very low. I turn off the car, restart, and all is normal. This does not happen on warm starts. What is this issue all about? Thanks, -Brian
Ok thanks for the input. How would the electronics affect the cylinders? Not sure if I understand what type of fault might cause this condition.
I had this issue on my 360. Fired up on 4 cylinders and run really rough, low idle. Then cleared itself and run normal. Only on 1st start of the day. Car ran perfect for years then developed this "overnight". Car was "over serviced" and I tried lots in attempt's to fix it as it really irritated me. I fitted a new battery (even though old one was ok). I had injectors cleaned. I cleaned my MAF sensors with the correct cleaner. I did battery reset and relearn procedure. No warning lights or CEL etc. Unfortunately nothing solved my issue. When I spoke to my dealer about the issue they said words to the effect that its pretty normal on the 360's and even some 430's do it..........??!?? Some say it is just the 2 ECU's not "syncing" as the car has 2 separate ECU's that effectively run 4 cylinders each (one for each side of the V). Take a look on the 360/430 forum and do a search for the same. I remember one long thread having the words "put put" or something to that effect in it. You should find lots of info regarding this on the 360's.
The issue is getting worse. Usually it goes away after a quick shut-off/ start back up. Today, in 39 degree weather...prob 45 in the garage, it took 4 restarts to clear the dogging idle. Of course, this NEVER happens when the car is warm. It has never happened after an ECU reset (battery switch off overnight). Again this is what happens: Turn key forward and wait for 6-7 seconds while things turn on and pressurize, start the car, idle is high, OIL STARTS TO REGISTER ON THE PRESSURE GUAGE and bam! my idle drops WAY WAY down to about 7-800 RPM, and the car chugs chugs chugs. Its like the oil is molasses, and it dogs the engine when it starts to flow. This is starting to be a semi-constant problem. BUT if I start it tomorrow it MIGHT do it, but it seems that it happens more after not driving the car. I drove it 3 days ago and it did it as well. Battery voltage is at 12.56 when off, and runs at about 14 volts while driving/idling. It has something to do with the oil...it happens as soon as the oil pressure guage starts moving, which takes 3 full seconds after starting the car. (seems like a long time, no?) Sure the oil is thick when its cold, but really? Why would it do this? The ECU theory seems plausible. But what does that mean ultimately? I need a new ECU? This one has me pretty stumped. Bad oil sender unit? Bad idle control valve? Squirrels in my motor? Any more feedback would be awesome. I have to get this solved.
I would do is find out if my WAG is correct that you are running on 4 not 8. First thing I would do is pull any codes. Misfire codes on one side saves you lots of work. If inconclusive, second thing when you get the chug chug put a timing light on the left vs. right spark plug wires and see if one side is dead. If you pass then three, alternately spray in some starting fluid on the left vs the right and see what that does to the idle. If indeed you are running on 4 you can now trouble shoot the bad side.
Have you replaced your MAF sensors before? I understand from other owners that MAF sensors can play a critical role in the idling of the engine.
Faced similar symptoms in my car. Cold start - engine runs rough and idling speed tends to hunt between 1.5-2k rpm. Rpm also drops to 500rpm, causing the engine to stutter at times. While driving, rpm climbs up to 2k rpm when I clutch in. Have to step on the throttle to bring down the idle speed. Was puzzled as my car just had full engine out service! Read elsewhere that MAF sensors may be the culprit. I bought some MAF cleaners, cleaned the insides of the sensor as well as the connectors in the engine bay. Swooped them over before I installed back. Mine's a 2.7. Voila!! Engine starts easily now and idles at a rock solid 1100rpm with A/C on.
I wonder if this is somehow battery related? It doesnt seem to do this after ecu resets. Lately ive been shutting off the battery after druves to conserve battery level. Just bought a tender. Will it work if the battery shut iff switch is turned to off?
I have the shop manual but not sure which section to look in to find where the mass airflow sensor is. Any pointers on where to locate these? Thanks!!!
thank you. The only code I get is AP 1448 but might bypass valve always seems to be working perfectly. Since I do not own a timing light I believe I'm going to check the mass airflow sensors first.
Try unplugging the cat temp ecu's. My car started running on 4 cylinders on occasion with no warning lights and it was my cat temp ecu. As my car has no cats, I unplugged both as they weren't monitoring anything anyway.
It is located right after the airboxes and before the intake manifolds, in plain view. A 5.2 car only has one MAF sensor. It's a large black cylinder. Made by Bosch 我從使用 Tapatalk 的 LT29i 發送
Here's a close up look of the MAF sensors for the 355. Covered in dirt and I presumed it was causing erratic readings to the sensors. Cleaned it up and I have not encountered any issues with cold start low idle/dogging. Image Unavailable, Please Login Image Unavailable, Please Login
thanks for all the feedback guys. Just took a look at the mass airflow sensor and that looks fine and quite clean. The connection pins seem to have some sort of grease down at the bottom perhaps as a way to protect from water damage. I'm wondering if I should replenish that? I'm going to clean the pins with contact cleaner and try and make sure there's no lithium grease on the pins themselves. While in there I also noticed that one of the bushings under my airbox needs replacement and one of the air boxes, specifically the one on the left, is drooping a little bit. I am wondering if this is interfering with my idle control valve which seems to have possibly a weak seal. I tried to loosen up some things and readjust the seal but not much luck. It seems to be less than idealbut I'm not really sure if this is the problem with my idle at startup Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
I have heard about leaking fuel injectors causing issues and just less than optimal injectors being a problem. How do you test and check the injectors?
You pull them out and have them blueprinted, no way for us to do it. I was thinking of getting the machine but lost interest. Should be done with belt service at minimum RC Fuel Injection
When discussing cleaning the MAF, people generally are referring to cleaning the wire inside the housing inside of the plastic mesh screens in your photo. Use CRC Mass Airflow Cleaner as directed on the can, available from any retail auto parts store. These cars also have issues with their electrical connectors. I've seen Deoxit recommended for them available at Radio Shack. I also have a spare MAF, I replaced mine a few months ago. I'm in NJ and you're welcome to borrow it to see if it changes anything. Disclaimer, I have no idea if my spare MAF is any good or not. I changed it as a maintenance item. If you decide to buy a new one, you can get a Bosch on amazon for about $135.00
Thanks for the feedback...and I appreciate the offer. I took a very close look at the wire inside the housing simply using a flashlight and it seems absolutely spotless
