Sputtering with Mach 4 Injectors

[ChuMaDD]

Why not try adding two capacitors in parallel instead of 1 large one? 1 set at the ECM and 1 set at the APPS. you would use 2 different sizes in the set 1 larger (lower freq) 1 smaller (high freq) to filter out the different spikes in frequency

 

[Ol Blue]

Will be interesting to see what happens when you add a filter at the ECM Rob. Also out of curiousity have you tried any of the other noise suppression techniques others have tried, such as splicing into the ground wire of the APPS harness and grounding to the dash, or the Navone filter (bulky) which I think goes to the PCM? Also in one TDR issue it talked about taking a wire from the alternator which runs through a wire harness and rerouting it or running a replacement by itself as a solution but the article wasn't clear on which wire that was.

During troubleshooting, the alternator was disconnected for a test drive. It made no difference. The spikes the ECM is seeing has to be coming from the conductor between the APPS and ECM. Perhaps from a sensor circuit like the cam sensor, wheel speed sensor, or other that isn't DC and runs close to the throttle circuit though I've checked grounds and have rebuilt some of them. I suppose there could be some missed. The resistance between body panels and engine, body panels and body panels, dash metal, pedals, etc. is just a few tenths. I've also checked the ECM case to engine block and negative battery cable. The only ground I've found that I "could" complain about is the driver's side ground cable at .9 ohms. I'll eventually get around to replacing it.

It'll all get done, and I'll just happen to see the one ground point I've been missing.... wned:

 

[Ol Blue]

Why not try adding two capacitors in parallel instead of 1 large one? 1 set at the ECM and 1 set at the APPS. you would use 2 different sizes in the set 1 larger (lower freq) 1 smaller (high freq) to filter out the different spikes in frequency

That's the plan. I started at the APPS because, well, it was easiest, and I was already there polishing the APPS bracket.

Multiple sized ca-zap-itors is a good idea, unfortunately, there isn't really a frequency to filter. It seems like random and comparatively significant spikes, hence the concept of a larger capacitor. When I get it back in the garage, I'll try both the 470uF adn 1000uF at the ECM.

I'm concerned about bonding the sensor ground to battery negative or chassis ground. I don't know how the sensor ground is run through (and through what) in the ECM. I'm worried about burning up a component. Your thoughts?

 

[VMacKenzie]

Random spikes sounds tricky, what sort of amplitude are you seeing? What about a zener diode to clip it? Or maybe a simple low bandpass filter (RC circuit)? but maybe you already mentioned that. I looked at this a bit but I'm not much good at plugging numbers into formulas to calculate ideal resitor and cap values Low Pass Filter - Passive RC Filter Tutorial

I would say maybe start cutoff at around 10 hz? The trick is not starting to cut off at too low of frequency otherwise you would probably dampen quick throttle jabs.

 

[crackerman]

The noise in any automotive dc system is generated by the alternator. Put a choke and capacitor on your alternator charge wire. The ac ripple will nearly disappear.

 

[Water_Lover]

I have the same problem when outside temps are low. I have been running the same setup for 4 years and it started last winter. You might be on to some thing with installing the capacitor on the apps. But what caused it to start in the first place could it be the VP getting old and weak.

 

[Ol Blue]

Random spikes sounds tricky, what sort of amplitude are you seeing? What about a zener diode to clip it? Or maybe a simple low bandpass filter (RC circuit)? but maybe you already mentioned that. I looked at this a bit but I'm not much good at plugging numbers into formulas to calculate ideal resitor and cap values Low Pass Filter - Passive RC Filter Tutorial

I would say maybe start cutoff at around 10 hz? The trick is not starting to cut off at too low of frequency otherwise you would probably dampen quick throttle jabs.

You linked ME to a tutorial on filters? bif

Oh, I guess I'll forgive you this time I guess so long as you make sure there's no snow or slick roads down there this week when I have inspections to make. LOL

 

[Ol Blue]

The noise in any automotive dc system is generated by the alternator. Put a choke and capacitor on your alternator charge wire. The ac ripple will nearly disappear.

As stated above, the alternator was completely disconnected from the rig and didn't change anything.

 

[Ol Blue]

I have the same problem when outside temps are low. I have been running the same setup for 4 years and it started last winter. You might be on to some thing with installing the capacitor on the apps. But what caused it to start in the first place could it be the VP getting old and weak.

Weak VP?
I don't believe so. We've tried new everything from sensor (IAT, MAP, Cam, along with Crank on the 01.5), (1) new and (1) rebuilt VP.

If it's only during cold weather on yours, try cleaning the IAT and measure the resistance at a known temperature. If it helps a little, replace the IAT.

Some values at temperatures (in Fahrenheit) - Resistance in Ohms from Geno's Garage (I think - got them a long time ago):

Temperature - Resistance
30-40,000
32-30,000-36,000
76-13,000
81-6,870
122-3,000
130-4,000


In the end, I really believe it's a dirty ground from a sensor or other computer somewhere. Speed sensors, ABS system maybe. Probably why it's taking so long to get the capacitors done....they're not the "real" answer, but a band aid because I haven't find the real problem (IMHO). I"m also uncertain what the circuit inside the ECM looks like, so just bonding the signal ground to the negative battery post could permit more current through there than the ECM circuitry should have.

 

[VMacKenzie]

You linked ME to a tutorial on filters? bif

Oh, I guess I'll forgive you this time I guess so long as you make sure there's no snow or slick roads down there this week when I have inspections to make. LOL

OK you can beat me up next time I see ya :bow: LOL

 

[DISTURBED]

Open

 

[Ol Blue]

Thanks Disturbed!

 

[Ol Blue]

I can't believe it this was 2 years ago! ....and it still isn't fixed. Here's what doesn't work in case anyone is looking at what not to try:

(1) Trying to filter the off idle circuit from the APPS to the ECM. More on this for Vaughn in a minute.

(2) Trying to remove noise on the 5 volt signal to the APPS (ECM pins 30 and 32) with a filter. I used a 220mF capacitor (I think was the size) and continuously measured the voltage on the 5V supply to the APPS. That supply remained as noisy as ever and the stumble did not change.

Since the 12V source to the ECM seemed to stabilize a little with the capacitor at pins 30-32 (which makes little sense), I immediately removed it to eliminate the possibility of doing harm to the ECM.

Next up will be a LARGE capacitor at one of the +12V supplies. Since these 12V sources all originate together, (1) capacitor should cover all of the inputs.

I'm sticking with a simple capacitor since they are easy to solder into the harness and if something of importance actually happens, I can then measure input resistance (assuming dc only is wanted as an output), and build a good pi filter to cover low frequencies.

So, that's what doesn't work. If someone has had the engine stumble and got it figured out, please post up. It might be another 2 years before I get back to trying something else. *bdh*

Now for Vaughn. You had asked if adding a capacitor to the signal circuit from the APPS to the ECM could delay the throttle action (snapping closed) to help reduce turbo bark. Though I answered in the negative, boy was I wrong!

The first drive was in town. I let off the throttle and had to clean my shorts and the seat when the pickup did not immediately return to idle. It only took a fraction of a second for the capacitor to discharge and the throttle return to idle, but that fraction of a second while in town traffic after blindly modifying the throttle circuit...sheesh! In that split second I had panicked visions of running over all sorts of things that would be in the way. So YES. You can slow down the throttle closing to idle, BUT don't use as large of capacitor as I had. I think it was 1000mF. The smaller one I tried first did nothing to delay the throttle. Something in between would be needed. Their sizes are in the above post but I can't see it right now to quote them correctly.

 

[Ol Blue]

Also done was a third ECM replacement, a cam sensor replacement, and a FASS 150 fuel pump/filter. None of them helped.

 

[torqueman]

I can't believe it this was 2 years ago! ....and it still isn't fixed. Here's what doesn't work in case anyone is looking at what not to try:

(1) Trying to filter the off idle circuit from the APPS to the ECM. More on this for Vaughn in a minute.

(2) Trying to remove noise on the 5 volt signal to the APPS (ECM pins 30 and 32) with a filter. I used a 220mF capacitor (I think was the size) and continuously measured the voltage on the 5V supply to the APPS. That supply remained as noisy as ever and the stumble did not change.

Since the 12V source to the ECM seemed to stabilize a little with the capacitor at pins 30-32 (which makes little sense), I immediately removed it to eliminate the possibility of doing harm to the ECM.

Next up will be a LARGE capacitor at one of the +12V supplies. Since these 12V sources all originate together, (1) capacitor should cover all of the inputs.

I'm sticking with a simple capacitor since they are easy to solder into the harness and if something of importance actually happens, I can then measure input resistance (assuming dc only is wanted as an output), and build a good pi filter to cover low frequencies.

So, that's what doesn't work. If someone has had the engine stumble and got it figured out, please post up. It might be another 2 years before I get back to trying something else. *bdh*

Now for Vaughn. You had asked if adding a capacitor to the signal circuit from the APPS to the ECM could delay the throttle action (snapping closed) to help reduce turbo bark. Though I answered in the negative, boy was I wrong!

The first drive was in town. I let off the throttle and had to clean my shorts and the seat when the pickup did not immediately return to idle. It only took a fraction of a second for the capacitor to discharge and the throttle return to idle, but that fraction of a second while in town traffic after blindly modifying the throttle circuit...sheesh! In that split second I had panicked visions of running over all sorts of things that would be in the way. So YES. You can slow down the throttle closing to idle, BUT don't use as large of capacitor as I had. I think it was 1000mF. The smaller one I tried first did nothing to delay the throttle. Something in between would be needed. Their sizes are in the above post but I can't see it right now to quote them correctly.

I was chasing same problem as this and resolved it on my 98.5. So much nicer to drive. Where r u guys powering your fueling boxes from which fuse number. My guess is #7 spot in fuse block. Try changing to #9 spot it resolved my problem instantly.

 

[Ol Blue]

Currently, there is no fueling box connected, but I'll try to remember that. Thanks!

 

[Ol Blue]

The 300C is down until it gets new tires, so Ol Blue is doing the commuting. This became more "urgent". Last night I took apart the adapter from the Timbo APPS to the OEM wiring harness and made sure each pin on both ends were clean and tweaked to make good contact. That seemed to help a little, but not enough. Tonight, I'll try the pins and connectors at the ECM.....hopefully. It's getting dark way too early.

 

[crackerman]

Another easy filter is a ferrite head with each wire hooked through it's own bead on the way into ecm.

 

[Ol Blue]

Thanks for the suggestions.

Since tightening the connectors helped some yesterday morning, and helped a LOT for the drive home last night, I suddenly changed directions. It looks like the problem might be loose connectors. I want to try tightening all of those first as a real fix, then if that doesn't completely resolve the stumble, it'll be back to filters as suggested.

The drive home last night (87 miles of highway and farm roads) was enjoyable. I'm stoked to get after the rest of the connectors. I should probably also disconnect the batteries and let the system discharge, then reprogram the APPS / ECM together with operating the accelerator pedal 3 times. Perhaps the operation of the APPS and ECM together int the morning is why it did so much better last night than yesterday morning.

 

[Ol Blue]

Don't buy Steelman deutsch connector removal tools! They break VERY easily. I went through 2 and managed to get 6 connectors removed from the ECM plug. They replaced the first one, but the second one that broke went flying out into the pasture somewhere.

In any case, those connectors were fine and I now seriously doubt they could be the problem. There is a bell shape on the end of the female pin for alignment and then above that the sides are bent in toward the male pin (like an hour glass) on 2 sides of the female pin that are fairly thick and have plenty of tension toward the male pin.

I hung a 2200mF capacitor from the +12V (pin #50) to ground (pin #49) and soldered a new ground wire onto it which is bolted to the engine block. No difference, so that will come back out. Note that there are (2) +12V supplies (pins 48 and 50) that are split in the loom so filtering either one gets both. Likewise with the grounds (Pins #49 and #30).

Hopefully, I'll get back at it this coming weekend. Since attempting to tighten up the connectors at the APPS made such a difference, the adapter that came with the Timbo APPS, will make it possible to remove the OEM square shaped plug completely. I plan on cutting that plug out and soldering the conductors together on either side of the plug together which will leave only the connector at the APPS.