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Timing help needed

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unclesam099

15+ Year Contributor
151
1
Aug 4, 2004
SE PA, Pennsylvania
Whenever I go WOT in 3rd gear to try to log, I end up knocking badly as soon as timing drops from wherever it was when I started (mid 20s) down to 20 or 19.

It never fails that as soon as I hit 20, the knock kicks in. That usually happens around 3200rpm or so in 3rd gear.

I'm wondering what it should look like as soon as I go WOT and if it should be going down right away? And should I try to keep it above 20? Boost isn't all the way there yet either, I'm only around 10psi when the knock comes on and running really rich on the WBO2.

Base timing is 5* BTDC. MAFT running blow-thru with 3" GM. 550cc injectors. 37psi base fuel pressure, 255hp pump.
 
Log is as follows:

4th gear, WOT only shows 96 or 97% on the logger (shows 100 on the SAFC tho, is that a problem?), WBO2 reads 10:1. Boost is at 8-10psi when knock hits. I let off because of (obviously) the excessive knock. Even with bringing the MAFT settings leaner, it doesn't seem to want to quit knocking.

Code:
<table>
<tr>
<td>TIMA</td>
<td>O2-R</td>
<td>TPS</td>
<td>MAFS</td>
<td>ERPM</td>
<td>KNCK</td>
<td>IDC</td>
</tr>

<tr>
<td>35</td>
<td>0.04</td>
<td>24.3</td>
<td>138</td>
<td>2219</td>
<td>0</td>
<td>8</td>
</tr>

<tr>
<td>33</td>
<td>0.02</td>
<td>26.7</td>
<td>201</td>
<td>2219</td>
<td>0</td>
<td>11</td>
</tr>

<tr>
<td>30</td>
<td>0.55</td>
<td>36.5</td>
<td>270</td>
<td>2250</td>
<td>0</td>
<td>14</td>
</tr>

<tr>
<td>29</td>
<td>0.72</td>
<td>52.2</td>
<td>315</td>
<td>2281</td>
<td>0</td>
<td>14</td>
</tr>

<tr>
<td>26</td>
<td>0.7</td>
<td>63.9</td>
<td>327</td>
<td>2313</td>
<td>0</td>
<td>17</td>
</tr>

<tr>
<td>26</td>
<td>0.8</td>
<td>92.9</td>
<td>365</td>
<td>2344</td>
<td>0</td>
<td>19</td>
</tr>

<tr>
<td>25</td>
<td>0.82</td>
<td>95.3</td>
<td>390</td>
<td>2406</td>
<td>0</td>
<td>21</td>
</tr>

<tr>
<td>25</td>
<td>0.84</td>
<td>96.1</td>
<td>415</td>
<td>2438</td>
<td>0</td>
<td>22</td>
</tr>

<tr>
<td>23</td>
<td>0.84</td>
<td>96.1</td>
<td>465</td>
<td>2500</td>
<td>0</td>
<td>24</td>
</tr>

<tr>
<td>20</td>
<td>0.86</td>
<td>96.5</td>
<td>509</td>
<td>2563</td>
<td>0</td>
<td>27</td>
</tr>

<tr>
<td>19</td>
<td>0.86</td>
<td>96.9</td>
<td>554</td>
<td>2625</td>
<td>0</td>
<td>30</td>
</tr>

<tr>
<td>16</td>
<td>0.86</td>
<td>96.9</td>
<td>604</td>
<td>2656</td>
<td>0</td>
<td>33</td>
</tr>

<tr>
<td>15</td>
<td>0.86</td>
<td>97.3</td>
<td>642</td>
<td>2813</td>
<td>0</td>
<td>42</td>
</tr>

<tr>
<td>14</td>
<td>0.88</td>
<td>97.3</td>
<td>711</td>
<td>2875</td>
<td>0</td>
<td>44</td>
</tr>

<tr>
<td>11</td>
<td>0.86</td>
<td>97.3</td>
<td>780</td>
<td>2875</td>
<td>14</td>
<td>50</td>
</tr>

<tr>
<td>9</td>
<td>0.86</td>
<td>97.7</td>
<td>818</td>
<td>3000</td>
<td>13</td>
<td>57</td>
</tr>

<tr>
<td>7</td>
<td>0.86</td>
<td>97.7</td>
<td>925</td>
<td>2875</td>
<td>33</td>
<td>60</td>
</tr>

<tr>
<td>2</td>
<td>0.86</td>
<td>97.7</td>
<td>1019</td>
<td>3250</td>
<td>32</td>
<td>68</td>
</tr>

<tr>
<td>3</td>
<td>0.86</td>
<td>97.7</td>
<td>994</td>
<td>3313</td>
<td>37</td>
<td>69</td>
</tr>

<tr>
<td>2</td>
<td>0.86</td>
<td>98</td>
<td>1050</td>
<td>3313</td>
<td>36</td>
<td>70</td>
</tr>

<tr>
<td>2</td>
<td>0.86</td>
<td>98</td>
<td>1038</td>
<td>3375</td>
<td>35</td>
<td>70</td>
</tr>

<tr>
<td>3</td>
<td>0.86</td>
<td>96.9</td>
<td>1126</td>
<td>3438</td>
<td>35</td>
<td>73</td>
</tr>

<tr>
<td>3</td>
<td>0.86</td>
<td>57.7</td>
<td>1013</td>
<td>3344</td>
<td>34</td>
<td>66</td>
</tr>

<tr>
<td>3</td>
<td>0.8</td>
<td>17.3</td>
<td>359</td>
<td>3656</td>
<td>33</td>
<td>9</td>
</tr>

<tr>
<td>28</td>
<td>0.84</td>
<td>10.2</td>
<td>69</td>
<td>3438</td>
<td>0</td>
<td>4</td>
</tr>

<tr>
<td>40</td>
<td>0.8</td>
<td>10.2</td>
<td>44</td>
<td>3406</td>
<td>0</td>
<td>4</td>
</tr>

<tr>
<td>40</td>
<td>0.8</td>
<td>10.2</td>
<td>31</td>
<td>3344</td>
<td>0</td>
<td>0</td>
</tr>

</table>
 
Too much timing. Pulling out "fuel" (that means airflow) on the MAFT or SAFC puts you into a lower airflow and a higher timing map. Try richening up your settings under boost and see if it helps.
 
I'm already at 10:1 or richer on the WBO2, so I can't add more fuel. That and I'm not on boost yet, it's only at 8 - 10psi when the knock starts.

I'm kinda thinking that I'm stuck with a fuel setup that the MAFT can't handle.
 
Stock ECU tune shows all the way down to 9.5:1. You can still richen it up. Would be rich as hell but it might be driveable then. The MAFT shouldn't have any issues running 550's they're not much bigger than stock. I assume you have the SAFC zero'd out and the MAFT for tuning? What're your settings on both?

Also your TPS reading is fine. The AFC shows 100 because you learned the sensors range of motion not its actual reading.
 
The AEM WBO2 only reads down to 10:1, but I know that it's lower because the car is sputtering. I can't richen it up at all because the car bucks if I richen it up.

MAFT Settings are for 3" GM MAF (blow-thru config), Base 0/B, idle +8, mid 0, high 0. I have to add 6% at 1000rpm on the SAFC to get my low trim to read near 100%. Mid and high trims are over 100%. Other than that, the AFC is zeroed out.

Running 93 octane. I have access to 100 at a pump nearby, I was considering trying that to see if I can run this like this to confirm/deny the timing problem.

Plugs are NGK BPR7ES (1 range colder than stock), gapped to whatever they come with (.032 or .030, something like that?).

Not sure the coolant temp, I can check that out on the logger tomorrow. Should be normal though. Intake temps are constant since the MAFT sends that signal.

I had the car at 0* base timing and even that didn't help me at all. I'm really at a loss on what to do.
 
unclesam099 said:
Plugs are NGK BPR7ES (1 range colder than stock), gapped to whatever they come with (.032 or .030, something like that?).

Remember, plugs are not gapped from the factory. You have to gap them before installation. Pull the plugs, replace them if necessary and gap them to 0.026 - 0.028".

Did you do a pressure test?
 
Check the knock sensor in the back for any discharge and replace if you find any. Remember that correct torque on the sensor is 17 lb/ft. Anything more than that and you'll pick up false knock. I don't think adding tons of fuel and drowning the motor is going to help. I'd also check voltage to your fuel pump to ensure that you have adequate fuel supply to the rail.

Finally, are you sure you adjusted timing in the right direction? I've seen a number of people think it was at 5 degrees when it was really at 10 or 15.

Keep us posted,

Andy
 
spyderturbo, I checked them before they went in. They are almost 10k old now, so I probably should put new ones in. They do come at .028" out of the box from NGK, and I did verify this before I put them in. And I really don't think that it's the plugs - the car runs pretty smooth otherwise.

I did a pressure test after I rebuilt my TB just before I started trying to tune this thing, and it holds just fine.

Coolant temp is 95*C and Air temp shows 25*C on the logger today.

andy, I will check the knock sensor, that is one thing that I haven't. I will assume it is stock since the car was not well taken care of by the previous owner. I looked at the tech section for info on how to install one, so that may be next on the list of stuff to inspect/replace. Fuel pump is a 255 hi-pressure and is hotwired, so I think that is totally fine. Pressure gauge reacts fine while revving the car as it should (underhood, can't check while driving).

Last thing, I checked the timing with a timing light. It was at the T indicator before, and I moved it to the 5* mark (halfway between the T and the 10). It was dead on 5 with the pin grounded.

And I agree, drowning the motor will not help. I intend to tune it to 11.8:1 and add methanol for safety and a little more boost when I am happy with the fuel only tune.

Would it be better on the MAFT to run a very lean baseline number and add fuel back in?
 
You need to lean it out (even if the timing is that advanced). 73% duty cycle at 3400RPM is way more fuel that your injectors can even deliver at higher RPMs. I bet the knock is from too much fuel and the timing is not the direct cause. Seriously 550's must be squirting a lot of gas at that high of duty cycle at only 3400RPM, (must be a very long pulsewith).
 
Kelton, I have tried that to the point of running 12.5:1, but I will have to try that again. Obviously, something is causing the car to knock like this and I have gone thru almost everything.

The logger must not react fast enough on the Palm because when I hit it, it only shows me up to 55% before I let off. Does it log faster than it will display?
 
How many variables are you logging? My Palm105 logs about 55 samples per second. Obviously this means if I look at 5 variables, It logs each one 11 times per second.

Is the knock any better at 12.5:1? Is the timing more advanced as you lean it out?

I'm still convinced that 70+% duty cycles on 550's at 3400 RPM is way to much fuel! Regardless of timing, that is just ungodly rich.
 
Ok, on the run home I tried running much leaner at WOT. No difference in the knock. I was -15% at 3000 and -30% at 4000 on the AFC (so -22% at 3500). I didn't see that the timing was changing much, or the IDC for that matter. The wideband was a lot leaner and I tried to pull fuel out whenever I saw it said 10. I will run another short log tomorrow with these settings.

I don't know how many I'm logging, but I think it's RPM, timing, knock, O2, IDC, the 4 fuel trims, and MAF reading.
 
I thought that a 4th gear pull would show the data a bit better, but I can do a 3rd gear pull.

I pulled fuel out with the base setting and the car doesn't like it at all, knock comes on sooner and it knocks when starting out in 1st gear from a stop.

I do need to check my knock sensor and now I have a battery drain to fix. UGH.
 
yo bro, i dont know if you answered this questoin or went through it already but it kind of seems like you have a boost leak..anyways, i would like to take a look at the car im over the walt whitman bridge, if you wouldnt mind coming by, plus tomorrow night is track night at atco raceway me and my buddy are heading down with his talon...but give me a call during the day if you want 8565034551 -jon

also i have a compressor and a boost leak tester at the house...
 
unclesam099 said:
I did a pressure test after I rebuilt my TB just before I started trying to tune this thing, and it holds just fine.

Post #12. Thanks for the offer Jon, but I think that I found the solution:

100 OCTANE FUEL!!

If only it didn't cost $7.99/gal...

Ok, so I'm running too much timing for sure since I was getting minimal knock with the 100 octane (9 counts). I'm seeing 95% IDCs in 2nd gear at redline, but 3rd gear is only 67% by 5500 or so, and I'm at 18-19psi on the MBC. Kinda surprising with with the EVO3 and 550s that I would be running out of fuel. I could turn the AFPR up a tad to lower that. I'm at 11.7:1 pulling 10% to 15% of fuel out with the AFC. Damn, if it were only that easy!!!

Next question is how low is too low of boost pressure to start spraying methanol? I will probably pull my timing back a few degrees as well and up the pressure on my pump from 100psi to at least 120psi (M5 nozzle currently, can get an M10 if necessary).

THANK YOU to everybody that has suggested something. It is great to have people help and keep brainstorming to troubleshoot this problem.
 
HOLY HELL the car runs like a raped ape on 100 + methanol!!!

I will get a log tomorrow on the way to checking my timing to see if the ECU is actually getting the timing that it wants (ie without the pin being grounded) and I will see the REAL timing curve, when octane isn't an issue.
 
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