Fuel Injector Test

[RSTurboFWD90]

I think my engine ('90 Turbo) bucks because of a fuel problem. It only bucks at cruise. When you step on it there is no problem. My fuel injectors all have proper resistance and you can hear them working. Can they still be causing this? How else should I test them to see if they are good?

 

[steve]

Steve, My ISC clicks continously (never stops) when I turn the key to ON. It's as if it never gets to the point that the ECU says it should stop. Is that normal?

No, that not normal. it doesn't take more than 2-3 seconds to home the ISC normally.

Also, I am a true novice with the logger and would like a few tips on what I should look for initially to analyze the bucking problem. Thanks. R

http://www.vfaq.com/TMO/
http://www.technomotive.com/prod/datalog/datalogger.htm#avail
http://www.hywell.org/plhelp/
http://www.pocketlogger.com/index.php?pid=params&type=dsm

To start try watching the all the main parameters with the engine nor running. The values should be stable. If they aren't you have ECU or sensor problems.

Steve

 

[RSTurboFWD90]

Thanks Steve. I'll follow up when I get my cable and figure out how to use it. Online instructions seem pretty clear. My ECU is original and never out of the car so I'm thinking it maybe dying. This problem has gotten increasing worse over the summer.

 

[steve]

As I keep telling people, if you have original capacitors in a 1G ECU, they have either leaked or they're going to. The sooner they are changed the less expensive it will be.

Steve

 

[RSTurboFWD90]

I'm back. First, I have not yet pulled my ECU to check/replace the capacitors. I get that I should do this soon and will. I promise Steve.

I have used my pocketlogger to view the engine parameters. Again, I am trying to determine why the car sputters at idle and cruise. All runs fine when you get on it. No CEL light, no codes stored. Here's a summary of my initial findings.

Key ON, engine off: All parameters are normal and steady.

Engine IDLING: Engine sputters. Checked all available parameters for strange behavior. I watched RPM, Timing and O2 for over 20 minutes as they are the most interesting. All other parameters are very steady. These three have a random cyclic behavior. RPM range is 720 - 820 rpm, Timing is 5-13 degrees BTDC, O2 0.04 - 0.96 v. The frequency of the RPM and timing signal is much higher that the O2 signal. The O2 signal frequency ranges from 1 to 0.2 cycles per second (cps) meaning it can stay low (or high) for 1 seconds or 5 seconds in a random fashion. The other two parameters are much faster at less than 1 cps.

Engine held a 2400 rpm: Engine sputters. Same three variables as above. Similar behavior except timing is very steady (35-37 deg BTDC) and more advanced and the O2 frequency is higher in proportion to rpm (1 to 2 cps).

One thing I noted is when I shut the engine off, and cool 30 minutes, then restart and idle, the O2 signal stays low for 45 to 60 seconds and then slowly climbs to high for another 180 seconds before it begins to cycle. If the cooldown period is only a few minutes, O2 starts high for 15 seconds or so before it starts to cycle. I was reading that maybe the O2 heater could be a problem.

At this point I am not sure if I found anything unusal or significant. I can't determiine if the O2 signal is causing the sputter or if something else is causing the O2 to be so randomly. I will have to figure out how to get a graph of the signals to my computer to show here.

Please provide me with some more things to check. This logger is nice.

 

[RSTurboFWD90]

Here's a 10 second graph of my O2 signal at idle.

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I'm concerned that it is not more regular and it may be causing the sputtering at idle and cruising.

 

[steve]

I tend to look at the FTO2 and the O2-R at the same time to see how well the sensor is reacting to the ECU dithering the fuel. In MMCd unchecking the box for nonlinear O2 helps.

Your graph doesn't look like a good O2 sensor to me, but there may be other factors.

Steve

 

[RSTurboFWD90]

I don't have MMCd on my Palm so until I can figure out how to get it and use it.....I ran the pocketlogger and here are two charts I produced. Top graph is O2, middle is O2 Trim, bottom is WBO2. There is about 15 seconds of data in each run.

This is at idle...

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O2 is very random with a range of 0.06 to 0.94, O2 Trim has a range of 35 to 60%, WBO2 is constant at about 19 (I'm not sure what this is though).

This is at 2400 RPM...

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A similar looking result. O2 Trim range is 0 to 50%

I really appreciate your time to consider my problem, Steve. Thank you.

 

[RSTurboFWD90]

These are questions with regard to the recommendation to use MMCd. I have loaded a copy from http://www.ecimulti.org/mmcd/ . It is ver. 1.71.01132005E.

I do not see the "O2-R" parameter listed. Where is it located and what is it (as opposed to the O2 parameter) ?

I do not see a box for nonlinear O2 to uncheck. Where is it located?

 

[akdsmer]

I have limited experience with your datalogger and the dsm parameters, but not to standard automotive datalogging. The update on your datalogger looks good and fast. The O2 sensor is NOT a problem. The O2 trim is working based upon your graph. The WBO2 is most likely for Wide Band O2 sensor, which probably is "filler" and doesn't mean anything since I believe you are just using your factory Narrow band O2 sensor.

I see in the two charts (O2 and O2 trim) that the O2 sensor is working. It may be skewed a bit, but likely it isn't and is reading correctly. Its response is fast enough that you can see the misfire you are feeling. Note the "hash" in the O2 sensor waveform. In the most simplest explanation, when there is a misfire or such, the O2 sensor will see this extra O2 pass the sensor unburned and display this as "hash" on the signal. The PCM is controlling the fuel trim, because if you compare the first and second graphs, (O2 to O2 trim) the PCM is adding fuel when the O2 sensor stays lean, and subtracts it as it starts to stay rich. A 15 second window isn't the best way to see the trend, but you can watch it and it should go up and down to as it adds and subtracts fuel to keep the O2 sensor cycling (which is only done to control both CO/HC and NOx emissions). Now the amount of fuel trim correction may be excessive, and someone with more experience with your datalogger will likely be able to tell you if 50% is middle road or if it's really adding 35-60% fuel (most unlikely) I would figure your fuel trim is probably pretty good. Now if the percentage is how much it IS adding, then maybe you have a fuel delivery problem because to add that much fuel. Have you checked your fuel pressure?

Someone want to chime in with the normal fuel trim on this? It would also help for you to explain what happened in the graph. Can you graph rpm so that we can also "see" when the bucking occurs?

The hash is a misfire though, and there is most likely a good reason for it such as fuel delivery (which can be masked by a "run-rich" high load fuel mixture), or ignition.

It's easy to identify such problems when you have a scope, We can watch the inputs and output from the PCM and see if any of those are showing a glitch. If no glitch is found on inputs or outputs, it's a mechanical fault such as secondary ignition, fuel or basic mechanical. It's a little harder when you only have datalogger info.

 

[RSTurboFWD90]

I follow your analysis of the graphs. I have read that the O2trim should be 100% average so I was thinking this trim plot shows the ECM is trying to reduce fuel on the average. But I don't have any experience here.

I have not checked fuel pressure. I apparently need a special tool (adapter) to install a guage. I did have a clue about the fuel delivery system though. When I changed the fuel filter a few weeks ago (after the car had not been started for over a week), there was no pressure in the line. Do you think it should have had pressure or should it bleed off in 10 days? This may be nothing but I had a concern about no pressure. The fuel pressure regulator control solenoid operates properly.

I am out of town on business for couple weeks and so I can't work on the car until I get back home. Thanks for your comments. I welcome any other thoughts or suggestions.

RB

 

[RSTurboFWD90]

I tend to look at the FTO2 and the O2-R at the same time to see how well the sensor is reacting to the ECU dithering the fuel. In MMCd unchecking the box for nonlinear O2 helps.

Your graph doesn't look like a good O2 sensor to me, but there may be other factors.

Steve

I replaced the O2 sensor and still have the same problem. So (as you told me) I pulled the ECU and found one capacitor leaking. Now this has to be the source.

 

[RSTurboFWD90]

After months of trouble and new parts, I had the ECU repaired and my problem is solved.

 

[Project2G]

How else should I test them to see if they are good?

Old thread but this may help anyone else.

To test the injectors you need a fuel pressure gauge and injector tester which will pulse the injector at pre-determined pulse width. You turn the key on until you reach max regulated pressure(making sure your pressure is the same on all cylinder when testing)
The injector tester connects to the battery and plugs directly onto the injector and you push the button and it will pulse the injector at a pre-determined pulse width for a programmed amount of time and then you compare the readings from cylinder to cylinder.
My tester is an OTC #3398 and has 3 pulse settings.
1 pulse of 500 ms, 50 pulses of 10 ms and 100 pulses of 5 ms
The tester sells for around $100.00.I have had mine for 5 years and my brother who works at a dealership uses the same one so I feel it is reliable.
The only way to truely clean injectors is to use a setup that connects directly to the fuel rail and the cleaner runs directly thru the injectors.The fuel system on the vehicle is disabled during the cleaning procedure.