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Runs great but no power

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Old 08-14-2018, 04:05 PM
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Runs great but no power

I have a speed density 350 tpi setup in a Fiero. It starts, idles, and drives fine at part throttle, once you get into the throttle it falls flat, acts like there is no timing advance or too lean or rich. I ran a Wide Band on it and it was showing about 10:1 so I upped the injector size and this leaned me out to about 13:1 and it feels better but still not right. Scan tool shows high 20's for timing advance. Fuel pressure holds steady at WOT at 43 psi. Also when this is happening I can feel a very slight surging. I do have he EGR blocked off. The injectors are some orange top Python brand and the chip was setup for 22#/HR and it did run great for about a month. I also am pulling about 15 inches of vacuum and this does not drop any if I raise the RPM when testing for maybe a backed up muffler (no cats). I do have a back pressure test gauge to try but have not done this yet.

Am I missing anything?
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Old 08-15-2018, 12:39 AM
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Re: Runs great but no power

Fuel, Air, Spark, Timing... that's all an engine wants.
Sounds like you have yet to check spark.
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Old 08-15-2018, 05:49 AM
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Re: Runs great but no power

I do have a good thick blue snapping spark. I have not checked the actual voltage of it with a scope yet. I also did not mention I went through all grounds and added a redundant ground as well as checked all computer grounds.
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Old 08-22-2018, 05:35 PM
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Re: Runs great but no power

I tested all injectors for resistance and they all are in the 14 ohm range. Still have to do the back pressure test.
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Old 08-24-2018, 11:20 AM
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Re: Runs great but no power

If it has cats, check exhaust back pressure.
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Old 08-24-2018, 12:38 PM
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Re: Runs great but no power

Originally Posted by GeneralDisorder View Post
If it has cats, check exhaust back pressure.
No cats, but feels like clogged cats, so maybe failed muffler. I should have time tonight to test back pressure although I have true dual exhaust so will only be able to test the one bank that has the O2 bung for the tester to go into. I may just weld on another bung onto the other side then I can use this for Wide and testing.
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Old 08-25-2018, 03:38 PM
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Re: Runs great but no power

Back pressure test showed 1/2 psi at idle 850 rpm, 1 psi at 2000 rpm, and 3.5 psi at 4,000 rpm and the pressure held steady. So this is good but only able to test bank one that has the O2 sensor bung to tap into. I am more concerned about bank two as the muffler is split at the seam. This was not there when I R&R'd the engine. I did feel both tail pipes at idle and they felt the same for output so I had me wife rev it up to about 2500 RPM and it does feel like bank two is putting out less pressure so I am taking this side off for further inspection. Below is the split in the muffler and also notice some bluing on it which is a lot more than bank ones muffler. I also noticed bank two had some residual smoke coming out of it after the engine was turned off and there was none at all out of bank one.
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Old 08-25-2018, 07:15 PM
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Re: Runs great but no power

The top side of muffler is also bulging and splitting at the seams but it must have just been from some back fires I was getting every once in a while when decelerating as I just test drove it with bank two exhaust removed and it is still flat when at WOT, let off the gas to part throttle and it goes a little faster. It is very drive-able and I can accelerate good enough to be safe but it is way down on the power it once had.

Things I have changed or tested for the ignition/timing with known good parts are ICM, distributor pick up coil, cap/rotor, plug wires are new, and coil.
I advanced the base timing until I get a few degrees of knock retard. Fuel pressure holds steady under WOT and running rich at 10:1 with original tune and upped the injector size in the tune to lean out then at 13:1. The injectors all test good for resistance.

I am going to weld an O2 bung on bank two exhaust then put it back together and do some more testing with a lab scope I borrowed.
Will test injector drivers, and ignition.


If anyone has suggestions on what else to test with the scope please let me know.

I do have some Bosch GenIII injectors I could throw at it they are the 99/00 LS1 injectors GM 12555894 or Bosch 0280155890. The current injectors arr orange tpo and say Python where a part number would be if anyone has any information on these please let me know, very little information on them that I could find and they are out of business. I guess they were Venom brand a 24lb/hr sold for 89-04 Mustangs per this link: https://www.americanmuscle.com/vehipefuin24.html & https://www.jegs.com/i/Venom/735/%23...10002/-1#qaTab not sure if they are worth leaving in there or not.
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Old 08-25-2018, 10:27 PM
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Re: Runs great but no power

Injector drivers look fine but did not see much change when creating a vacuum leak or putting propane into this same vacuum line maybe not a big enough port just used the vacuum line off the plenum.

Primary ignition looks very dirty when at WOT other wise looks good.
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Old 08-26-2018, 08:47 AM
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Re: Runs great but no power

Originally Posted by Wickydooda View Post
Fuel, Air, Spark, Timing... that's all an engine wants.
Sounds like you have yet to check spark.
Add to that, compression.
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Old 08-26-2018, 09:59 AM
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Re: Runs great but no power

OK just did a compression test.

Cyl 1 - 155psi - Cyl 2 - 175psi - Cyl 3 - 175psi - Cyl 4 - 172psi - Cyl 5 - 170psi - Cyl 6 - 150psi - Cyl 7 - 160psi - Cyl 8 - 172psi
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Old 08-26-2018, 10:36 AM
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Re: Runs great but no power




Since I had the plugs out for the compression test I figured I would post them they all look the same and are at .035 gap.
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Old 08-26-2018, 11:34 AM
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Re: Runs great but no power

Here is the secondary ignition waveform first one is at idle and the second one is at WOT under load.


I am certainly a newbie using a lab scope but does not look right comparing wave forms in manual and reference waveform on this scope and the duration appears to be very low.
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Old 08-26-2018, 11:48 AM
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Re: Runs great but no power

You need to correlate the ignition waveform to which cylinder it's firing. You definitely don't have consistency there. But without knowing which waveform belongs to which cylinder

Do you have a second channel on the scope that you could monitor the #1 plug wire to use for a trigger? Either that or monitor them one at a time.

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Old 08-26-2018, 11:57 AM
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Re: Runs great but no power

The inductive clamp was on number one. Looks like I could do a parade pattern that will show all cylinders based off number one and display in the firing order. There is a second channel on this scope but not sure how I would connect this. Or I could just keep testing and move the inductive clamp to every cylinder.
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Old 08-26-2018, 12:20 PM
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Re: Runs great but no power

Here is how I am connected for secondary ignition testing and the first scope image is idle and second is WOT. It is a OTC 3840F scope.



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Old 08-26-2018, 12:50 PM
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Re: Runs great but no power

Can't really see anything useful without zooming in on the firing line and also comparing it to other cylinders. I would at least try to compare it to the highest compression cylinder being that #1 is the lowest. Can you save a log an open it on a computer to see more details? Do a google image search for secondary ignition waveforms. Can learn a lot looking at waveforms from known conditions.

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Old 08-26-2018, 01:27 PM
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Re: Runs great but no power

I'll try to change the time or voltage and see if I can get a larger pattern.

Thanks
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Old 08-26-2018, 02:39 PM
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Re: Runs great but no power

Idle

WOT 2 parts so you can see each cylinder closer unfortunately the resolution sucks I'll make another run.

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Old 08-26-2018, 06:29 PM
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Re: Runs great but no power

Need more resolution or zoom in.... can you change the meter to a 5ms sweep?
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Old 08-26-2018, 07:06 PM
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Re: Runs great but no power

Yes, this was the closest I could get with at least 8 cylinders showing then I took a picture of the first 4, and the last 4.
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Old 08-26-2018, 08:15 PM
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Re: Runs great but no power


Here is WOT parade at 5ms
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Old 08-27-2018, 10:21 AM
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Re: Runs great but no power

It's all still too compressed. Can't see enough detail to make any observations. This is what we need to see:

I'm guessing that the 5ms on your scope means that your graph is 5ms granularity. Try 1ms or even 0.5ms if you have that.


Last edited by GeneralDisorder; 08-27-2018 at 11:16 AM.
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Old 08-27-2018, 10:18 PM
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Re: Runs great but no power

Here is 1ms and I did it in single cylinder mode, the parade pattern compresses it for all the cylinders and it is a small screen I can just do each cylinder this way. Still does not look right once I do a WOT run, at idle it looks normal with voltage per division at 10kV and 1ms.



Thanks for the help!
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Old 08-28-2018, 04:44 PM
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Re: Runs great but no power

Is that idle or WOT and just cylinder #1?

Honestly it looks fairly normal. The resolution of the scope leaves much to be desired and it seems like there is significant irregularities from event to event of those traces are for the same cylinder?

It looks like the peak KV isn't showing on the scope - like it got lost in the scaling or something.

Have you considered a laptop based USB scope? Something with a much higher resolution? They are pretty cheap on ebay these days.
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Old 08-28-2018, 07:44 PM
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Re: Runs great but no power

Yes WOT cylinder 1 only. I have noticed the Fire kV and rpm during parade getting lost.

Here is another I think looks much better at 10kV scaling and 1ms. If this looks like the right setting I can start switching cylinders. I will certainly look into a USB scope if it will help here.

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Old 08-29-2018, 10:38 AM
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Re: Runs great but no power

Secondary ignition can be tough to read but it looks lean. The firing line is very hashed up. This usually indicates a lean condition. It can also be low compression or a cam lobe issue.

The low manifold vacuum is concerning, and the compression numbers are pretty ho-hum. A good compression number on a TPI engine is around 195.

Another easy test is to check the temp of each exhaust runner (easier if you have headers), with either a laser temp gun, or even better a thermal camera.

Given what you have tested so far, I would pull the injectors and have them tested. That needs to be ruled out and injectors are often a problem for TPI's. If that doesn't make much difference the engine is probably due for a rebuild.

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Last edited by GeneralDisorder; 08-29-2018 at 11:21 AM.
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Old 08-29-2018, 11:40 AM
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Re: Runs great but no power

The wide band with original tune that did run great looks rich. I agree with the spark line going this high it looks like a fuel issue and was thinking injectors may be the issue with these off brand Venom/Python brand and this appears to confirm it. I have some injectors I can try and an AFPR I need to put on anyway so will get to it!

Thanks for all the help!

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Old 08-29-2018, 02:13 PM
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Re: Runs great but no power

These engines are known to run extremely rich (in the 10's) on the factory tune at WOT. But wideband readings are all cylinders mixed together and if one goes lean it's going to cause all the other 7 to go rich and the lean (now slightly less lean) cylinder will be lost in the overwhelmingly rich conditions of the other 7. The problem is that none of the fuel trim or AFR data can be trusted since it's all derived from a single airflow calculation that assumes all cylinders are breathing EXACTLY the same amount of air, and that all injectors are flowing EXACTLY the same amount of fuel. So if those two assumed variables are inconsistent from cylinder to cylinder, you get this situation where nothing makes any sense from the sensors. The one thing you can rule out easily is the injectors, and if that doesn't do the trick then it's going to be cylinder balance which is mechanical and is going to require a tear-down.

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Old 08-29-2018, 02:27 PM
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Re: Runs great but no power

Thanks again. Scanning this all looked as it should this is why I went deeper with the wide band, then leaned it out from the original tune but still not right so the scope was next, the setup of the scope getting right was the biggest hassle for me. Hoping I can run her with the engine the way it is for a while and play with the tune.
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Old 08-29-2018, 03:44 PM
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Re: Runs great but no power

I can see from the plugs that it is rich any oil on those?
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Old 08-29-2018, 04:19 PM
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Re: Runs great but no power

Yes likely some oil as I do have some oil on restart like the valve seals are leaking.
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Old 09-05-2018, 05:58 PM
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Re: Runs great but no power

Well it was not the injectors. Installed some 0280155710 injectors and tuned for the offsets and it does have better throttle response but still goes flat anything above about 25% throttle.

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Old 09-05-2018, 06:08 PM
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Re: Runs great but no power

are you able to log data in TunerproRT? if so maybe send a log my way... hopefully has WB data in it too...

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Old 09-05-2018, 06:21 PM
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Re: Runs great but no power

How does your TPS voltage look?

A crummy TPS can cause symptoms like what you describe. IIRC, idle voltage should be .54, and with a scantool, you should see a smooth rise as the throttle is opened.
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Old 09-05-2018, 06:49 PM
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Re: Runs great but no power

I will have a ALDL cable tomorrow and be able to log. I do not have a cable for the Innovate wide band yet I will get this on the way so it can log with it. I can at least watch the AF.

TPS looks great, at .54 and smooth transition to WOT. I cannot see anything obvious with the AutoXray AX6000 everything appears as it should and no codes.

If the distributor was sloppy enough could this be causing it not to get the timing it needs? The pick up coil and ignition control module are new, and I tried another ICM I had as a spare and changed the pickup coil to hopefully help with this as it looked pretty old with a very brittle connector.

Going to see where my AF is at now and run the scope as well.
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Old 09-05-2018, 07:28 PM
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Re: Runs great but no power

Watching the TPS and it is at 50% where it falls flat exactly where PE is set in the tune. The AF meter was not cooperating sometimes would work then would go to 7.4 in bold then stick there, then start reading again.
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Old 09-05-2018, 08:01 PM
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Re: Runs great but no power

Is the air fuel meter using a 5v wideband or the 0-1v factory narrow band? When it goes into PE it's going to be far too rich to read anything useful on a narrow-band sensor.

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Old 09-05-2018, 08:11 PM
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Re: Runs great but no power

are you actually GETTING into PE?
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Old 09-05-2018, 08:53 PM
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Re: Runs great but no power

It is a Innovate LM2 wide band setup.

Not sure how to tell if I am getting into PE?
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Old 09-05-2018, 08:59 PM
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Re: Runs great but no power

The O2 goes to .860 mV, I could check to see if going to open loop but assume it is.
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Old 09-05-2018, 09:13 PM
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Re: Runs great but no power

couple of indicators...

On the scanner the BLM and integrator should lock to 128.

also, the commanded AFR should drop to something a lot lower than 14.7... probably somewhere around 11:1 for a factory calibration.
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Old 09-05-2018, 11:00 PM
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Re: Runs great but no power

I will check this out tomorrow am. I would think loop status going open and o2 not switching would also indicate pe. I do not get commanded AF with the AX6000. But hopefully will with Tunerpro RT.

I feel like switching pe to 75% would be better
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Old 09-06-2018, 10:37 AM
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Re: Runs great but no power

What's your plug gap?
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Old 09-06-2018, 11:24 AM
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Re: Runs great but no power

.035
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Old 09-06-2018, 11:50 AM
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Re: Runs great but no power

Does your scan tool show any knock retard? Does it show knock counts?
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Old 09-06-2018, 01:06 PM
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Re: Runs great but no power

It does show some knock retard, I get 3 degrees on retard where the timing is at now, and I am not even sure exactly where that is as I have been messing with it and have to jack the car up and remove the rear right wheel to see base timing because the engine is right up against the frame rail. I can retard it a little and the knock goes away. When I originally put the engine back in it felt the same way it does now at 6 degrees base timing, I advanced it and it was night and day and the car ran great for maybe 600 miles then its like it came back and this is why I was sure it was a timing issue.

The tool does show knock counts but I am not really sure what this is for, maybe how many times it has pulled timing for knock would be my best guess. Please elaborate on what the knock counts are for. I want to say this was maybe in the 20's yesterday when i did a test run.

I will not be able to do a data log today but will have all day tomorrow and will be able to use TunerPro RT as I should have an ALDL cable today from 1320electronics.
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Old 09-06-2018, 02:03 PM
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Re: Runs great but no power

Knock counts are just an indication of how many distinct knock events the sensor is registering. When you see these, listen for the sounds of pinging, etc. If you don't hear anything, you can try disconnecting the knock sensor and see if anything improves about the feel. It could be false knock - something loose or noisy in the engine that is setting off the sensor but isn't actually detonation.

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Old 09-06-2018, 02:07 PM
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I'll try it tomorrow hell I'll try anything at this point! I did borrow a Bosch lab scope also so maybe I can get a better wave form image.
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Old 09-06-2018, 02:45 PM
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Re: Runs great but no power

What do you have your MAP threshold set to for PE entry?
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