Just recorded my first data log. I recorded from a cold start to warm, then rev'd the engine a few times. I didn't drive the car at all. As you can see, I didn't switch it to the higher baud rate until it was already warm, so I missed out on a lot of data from cold to warm, but now that it's warm, I'll have to wait to get another cold start reading.

I have a 305 TBI.

Can someone please take a look and tell me if anything looks wrong? Everything seems fine to me, the sensor readings seem OK, but this is my first time ever data logging, so I'm not sure.

I do have a problem where cold starting takes about 2 seconds of cranking. Also have a very slight misfire or vacuum leak. The RPMs sometimes go up and down maybe 100RPM at most. You can barely see it on the tach. It's weird, while I had the winALDL cable plugged in, the idle was super steady. So maybe it's a timing problem?

I also have a problem when I'm driving, if I put the pedal to the floor, it accelerates just the same as if I was slowly pressing the pedal to the floor (RPMs slowly go up). Then after a second, the RPMs suddenly jump all the way up to 4-5K RPM, instead of smoothly going up. Again, didn't happen now in park with the cable connected. Maybe timing then?

Thanks. I'm exciting to get into tuning, so feel free to educate me on anything.

 

Initial timing could be changed to help on the long crank. I assume it is set 6 deg at dist and same in .bin. If not move both to 6.

Adding more crank fuel in .bin is going to help.

Verify no vac leaks.

 

Sorry, I'm completely new to this. What exactly is .bin and how do I modify it? Is it something in the ECU? I thought I needed more than just the ALDL cable to modify my ECU.

Actually my timing is at 0*. That's what my hood sticker says to put it at. I have a 92 RS 305 TBI. I know most cars I've seen with TPI engines say to set timing to 6*. I probably could get away with 6* too, since I have headers, new cat, and catback. But shouldn't the car start fine with 0*, since that's what it's supposed to be stock?

 

Some updates are in my thread in the General Engine thread.. I bumped timing to 6*, cleaned battery to chassis ground, and replaced all spark plug wires. Car runs better, but still has the problem. When I disconnect the O2 sensor, and computer is in open loop mode, the problem doesn't seem to happen.

Here's a tunerpro RT datalog this time (.XDL file). I noticed Tunerpro seems to capture the data with more frequency and less latency than WinALDL. I'm still trying to figure out the graphs and all the cool views I've seen in screenshots.

I was idling for a long time, but you should see 3 WOT passes. 1st one, no problem. 2nd one, it bogged and was reving very slowly past 2K rpm. 3rd time, no problem again.

 

I took a look at your data log... $61 doesn't give a ton of information unfortunately... and I'm a lot more familiar with $8D than anything else, but these are some of my observations...

1.) Your BLMs are low... down around 113-118 at idle. But it'll randomly then jump up to 124-128 (which is ideal). Is the car stock? Something appears to be making the car run rich and causing your ECM trim the fuel mixture lean. Definitely verify your ignition components (cap, coil, rotor, plugs, etc) and your spark timing. Poor ignition quality is definitely a suspect here based on your description of the problem.

2.) I see no read out for spark timing, so I have no idea what you're set at. Do you have a dial back timing light?

3.) Does your car have crank sensor? The crank sensor pulse flag is intermittently on and off. Not sure what that means.

4.) I'm seeing significant changes in engine speed without a corresponding change in throttle position. Since the IAC steps are going down at the same time, it leads me to believe you may possibly have a faulty TPS (not always reporting throttle position accurately to the ECM). Could explain the intermittent bog your feeling. ECM relies on that to deliver the "accelerator pump shot" (to use carburetor terms). MAybe with the engine off, key on, Tunerpro running, move the throttle blades and monitor the TPS to see if you get any instances of throttle movement without voltage increases.

5.) You're Park/Drive status is stuck in drive. Since I'm not seeing increases in vehicle speed corresponding to RPM changes (which means you're in park), leads me to think you have a faulty sensor or connection in that circuit.

4.) I don't see any codes being set

 

Thanks for taking a look..

1) Yeah I noticed that, odd indeed. I did double check ignition components, all the ones you mentioned except the pick up coil. Also the distributor has some vertical play, even when the hold down clamp is tightened. It's not like when the clamp is loose and you adjust the timing. It's more of a vertical, up and down, towards the front and back of the car. My friend was saying I should just replace the whole distributor.

Could a timing chain cause this? I have 200K+ miles and it looks like there's a small oil leak from the timing chain cover.

I just put brand new wires since the old ones got burned on the headers. Haven't checked plugs to see if they got fouled though. Car is stock besides headers and catback. Also have MSD ignition components if it matters.

I've been thinking it's an ignition problem, but I have so many new parts, and it runs fine in open loop.

2) It's set at 6*. Yes, set it with EST connector disconnected. No, I don't have a dial back timing light.

3) I don't think it does. I have never seen one. I didn't know any of these thirdgens even had them.

4) When you say move the throttle blades, you mean by using the accelerator pedal right? But yeah, I did exactly that, and the TPS was fine, it was moving up and down smoothly, and also the min and max values were good.

5) Well my shift indicator cable is bad. (I have a B&M shifter). Something happened while I was installing some other shifter parts, it got stuck and wouldn't move. Now it moves every once in a blue moon. I have a new one, just been too lazy to install it. I thought it was just for the indicator window anyway.

What sensor or connection tells the car it's in park or drive?

 

I would think a really worn timing chain can cause erratic spark timing, and could affect BLMs. But I'm not sure I'd go to the trouble of replacing it yet until all the other "low hanging fruit" is picked. Definitely check your plugs.

Maybe pull the distributor out and look at the gear. If that's seriously worn, I'd definitely replace that. Could be the cause of the play. May not need to replace the whole distributor assy... Also with it out, if you can, grab a flash light and see if you can see the cam gear well.

For the park/drive, sensor is probably a bad term on my part. If it's like $8D, there's a wire coming off the ECM such that a switch on the shifter grounds it. I forget if grounded = park or grounded = drive. But if that connection or switch is faulty, the ECM will think you're in one or the other (in your case, Drive).

Yeah, I'm not sure what the crank sensor thing was all about in the data either... maybe someone more familiar with $61 knows.

If your TPS is verified good, I'm not sure what could be causing the RPM to bounce up... it's shooting up by ~700 rpm with no change in TPS at a couple of points in the data. Some intermittent vacuum leak somewhere perhaps? I'll look at the data again tonight and see if the jump occurs simultaneously with something else... might give a clue.

On the TPS, maybe fully warm up the car and repeat the test. Electrical equipment typically fails over temperature when things start moving around with CTE. Could be the TPS is fine at ambient temperature, but faulty when hot.

 

Thanks again.

I will look into the distributor. Most likely the pick up coil and gear are both bad.

Oh, I know what the park/drive sensor is. Right next to the reverse switch. It was working the last time I checked down there, but I'll take another look.

I doubt it's the TPS getting hot. The problem happens when the car is fairly cold. Like the latest datalog I posted, I started the car, and almost as soon as it went to closed loop, I tried it out, and the problem already was occurring. Plus I checked the TPS when I came back and it seemed fine.

Also forgot to mention, I swapped my rear end. I didn't count the gears of the new or the old one, so I don't know which one is which. But I'm pretty sure I have a slower gearing now because the speedometer reads slower than I'm actually going. I didn't notice if the datalog speed readings are off or not. Would this have anything to do with it?

Also I do have a small vacuum leak occaisionally from the heater controls. I'll move it and it'll hiss. I just have to move it back and forth again and it'll go away. But it doesn't just pop up randomly, only if you change the heater setting. So I don't think that's the problem.

Also still puzzles me, why does it run so much better in open loop? There must be some sensor or something with the computer messing up