Trouble starting, then very rough idle and backfires (Page 3/4)
Patrick FEB 19, 02:48 AM
Damn.... slow down! Do some more basic stuff first before you start pulling heads etc!

When you're changing the plugs, that would be a good time to do a compression check on the cylinders... and check the resistance of your spark plug cables while you're at it.

In regards to setting up a laptop to work with WinALDL... it's relatively simple, but... sometimes it's a little tricky to get anything to register on the laptop due to COM settings. Give it a whirl and if you have any trouble, yell here for some help.

[This message has been edited by Patrick (edited 02-19-2024).]

82-T/A [At Work] FEB 19, 07:38 AM

quote
Originally posted by WingsGT:

Would it be unreasonable to take the cylinder heads off and have them rebuilt, and replace the timing chain myself at this point? It doesn't seem like it would be a crazy amount of money since I found a place that said they could rebuild heads for $100 each, which I found kind of surprising considering other quotes I got in this area but I think they're legit. I really want to keep the cylinder heads in good condition for a 3.4L swap down the road. I've been trying to learn stuff gradually in the hopes I would be able to handle that swap comfortably by the time something major failed on the 2.8, but now here we are.




Wings GT... I'm going to have a set of 2.8-3.4 HO heads that have been completely rebuilt, which I will not need, and will not be using.

In short, I bought a 3.4 V6/60 long block, in which everything has been refreshed, and then I ordered a set of ported ARI Racing Heads w/ Swirl-port valves. So I won't need this extra set of heads (which are totally machined and fitted with new valves). Only thing, it's going to be a couple of months before I swap them out, but you can have them for free if you want them. I am also located in Florida...

[This message has been edited by 82-T/A [At Work] (edited 02-19-2024).]

WingsGT FEB 19, 09:52 PM
Haha, I know Patrick. Not actually going to do all that right now. New plugs are on the way. Couldn't find the serial-USB converter I thought I had so I ordered a different one with flying leads and the chip in the USB side. I will continue with troubleshooting the parts I have, just sometimes starts to seem like I'm looking for issues that would be irrelevant after doing other things I might want to do in the future. But if it is something else I need to figure it out now.

Thanks 82-T/A, I appreciate that and it makes me feel better about blowing these up if it comes to that. Probably shouldn't be so precious about the 2.8 heads since anyone swapping anything other than the 3.4 would also be getting rid of them. Not to derail but what are you doing for the intake on your 3.4?
jelly2m8 FEB 20, 02:31 AM
Definitely do a compression check while the plugs are out if you have the ability for that, that may eliminate a worse case scenerio.
WingsGT FEB 25, 01:50 AM
Gonna do the compression check soon, new plugs just got here.

Question on the WinALDL cable. I want to use 5v VCC from my USB adapter instead of the 12v battery or serial DTR pin like the diagrams on the website show. I've been trying to figure out if I should use a different resistor there, but now I'm thinking it's just a pull up resistor and I should stick with the 10kohm. That would be easier and in theory keep everything 5v on the serial converter side of the transistor, but is there any problem with doing it this way?

Will WinALDL be able to read sensor data with the key in accessory? We were talking about which sensors might have caused this by failing suddenly, and that's probably the only way to rule out the O2 sensor right? Does the ECM even use the O2 sensor before ignition? But otherwise, I checked the intake air temp sensor and it read normal at room temperature. Haven't checked the coolant temp sensor yet. Should I also check the cold start temp sensor? Or anything else?

[This message has been edited by WingsGT (edited 02-25-2024).]

Patrick FEB 25, 02:35 AM
I don't understand your questions about the cable.


quote
Originally posted by WingsGT:

Will WinALDL be able to read sensor data with the key in accessory?



You mean the key just turned to "RUN", without actually starting the engine? Some of the sensors will function.


quote
Originally posted by WingsGT:

...that's probably the only way to rule out the O2 sensor right? Does the ECM even use the O2 sensor before ignition?



You're not going to get any pertinent readings from the O2 sensor unless the engine is running. Same thing with the MAP sensor.


quote
Originally posted by WingsGT:

Should I also check the cold start temp sensor?



It's not a sensor, it's a temperature controlled switch. If you're concerned that it might always be "closed" (doubtful), just unplug the harness from it.

[This message has been edited by Patrick (edited 02-25-2024).]

WingsGT FEB 26, 01:39 AM
Ok, just trying to rule out things out for sure where I can. So O2 sensor readings wouldn't affect starting. I've been looking for more info on the cold start injector and its switch, can't find what temperature it's supposed to switch at but it sounds like the injector is always active when cranking so the switch also would not affect starting.

I built the WinALDL cable the way I was describing and I'm getting some data through (with key on run) but it isn't populating into the sensor fields. Have you seen it do this before? I just have this on the RAW Data tab and nothing on Sensor Data. I'm thinking this at least means I got the wiring right because the data doesn't look completely random, but I'm not totally sure and it also could be a problem with the USB converter I'm using.
Patrick FEB 26, 02:05 AM

It's been so long since I've used the program, I'm afraid I can't be of much help. Make sure to use ALDLView though to see the info displayed in a manner that'll make some sense.


quote
Originally posted by Patrick Here:

The first thing I like to check is that both the Manifold Air Temperature and Coolant Temperature sensors are working properly. After the car has sat all night, see what the readings are. You can plot multiple readings on the graph at once, and ALDLView will also save GIF's of what you're looking at.

Here's an old reading I just randomly grabbed of my Formula. Notice how when the engine starts, the two temperature readings are very close to each other.
WingsGT FEB 26, 08:22 PM
Oh sweet, didn't know about that. Will definitely use that when I get some readable data.

I'll have to try some different things with the WinALDL cable, see if I can get a resistor across pins A and B for diagnostic mode. Found some other posts here that said that was the only way it worked. But the ALDL plug I have was made for something else and doesn't have a wire for pin B, so I'll have to figure that out.
Stingray92 FEB 26, 08:58 PM
I would suggest starting a list of what you've confirmed to be in working order. Follow it up by what you're observing.

Instant/overnight symptoms are rarely mechanical. Check for bad grounds/corroded electrical connections on the ignition system. Just as others have already stated.