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Conflicting EGT Information (Very Long)

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andymoraitis

15+ Year Contributor
3,241
153
Jan 25, 2004
Utica, Michigan
I'm hoping that some of you more experienced tuners can give me a hand in understanding what is correct for my setup. Let me preface this by saying that I am fully aware that an EGT is not a tuning device since high readings can be seen by running rich or lean. Anyway, let me post my setup and my questions.

1998 GSX AWD
Injen Intake with 4" filter
Big 16G Turbo
Walbro 190 Fuel Pump
Buschur Upper I/C with 1G BOV
Full 3" Exhaust with 3" High Flow Cat
Stock Injectors
Buschur MBC
Stock SMIC
95 EPROM ECU with KeyDiver Stage III Chip (no fuel cut)

Here we go. This car was pretty much a mess when I bought it and after I took a trip to Buschur Racing, Dave and Dan installed the upper I/C, BOV, MBC and changed the plugs and wires, it ran like it was supposed to. Boost was set at 15 psi since I still had the stock pump although it would occasionally creep to 16. In speaking to Dave he told me that with a 190 pump on 93 octane that I could run 17-18 psi safely. Within the next month or so, I added the 190.

As colder weather hit, the car wanted to creep more (up to 3 PSI) so I called Dave and also Mike Welch from RRE and both of them advised that I set the boost to the point it would creep to and see if that solved the issue. So I set it to 17 and it only creeps to 18. I noticed my EGT's would rise rapidly and peak at between 1580-1610 at the top of third gear. I got back to Mike at RRE who told me this is where I wanted to be and Dave who red flagged it and said I need 550's.

What concerns me is the info on RRE's website that says that 17-18 psi on a fuel pump upgrade with 93 octane is OK while Dave is telling me I'm in the danger zone. I've also referenced some additional threads in which other tuners are running close to 1600 or more at the top of third and no one seems to think anything of it. As a safety precaution, I've ordered a set of 550's which will be going in this week as well as a new DSMChip to compensate for the bigger injectors and fire them like stock 450's (with a deadtime adjustment).

You guys MUST be tired after reading all of that, but bear with me as I have two questions:

1. Did I just waste a few hundred bucks when I could have kept the car on stock 450's?
2. I noticed that most people tap their EGT probes on the top of #1 runner. Mine is tapped on the side of #1 (it was already installed when I bought the car) and I'm wondering if this isn't causing me to have higher readings.

As a form of checking whether I'm rich or lean, I pulled all four plugs and all of them have tan electrodes and no sign of running lean whatsoever. As a matter of fact, #1 looked as good as #4.

Again, sorry for the length, but I would appreciate some factual information regarding the above. Thanks in advance!

Andy
 
You were going to need bigger Injectors anyways to run the 16g to it's full potential, so no you didn't waste any money. Also the Probe being on the side shouldn't really matter.

Once you get the new injectors in leave the boost where it is till you get a FMIC.
 
Many thanks for getting to the main issues. I'll let you know how it goes once the new injectors are in and I'll be sure to upgrade that SMIC in the future, or maybe even install water injection.
 
As he mentioned, you didn't waste your money. It is always better to be on the safe side. I know I personally would not run 17 to 18psi on just a pump upgrade as your likely to be maxing out those 450's. As to your question about the high EGT's, Mike is right in that that is about where you want to be. On my car, I'm seeing around 860-870 at the top of third gear on pumpgas with no knock. High EGT's can mean knock (IE your running lean - which is why i'm sure Dave raised a flag), but in your case, if you have checked the plugs and do not see any sign of detonation, you should be good to go :) I would invest in a logger of some sort though so you will be able to atleast monitor your timing since 2g's can't monitor knock. As long as you havn't hacked any of your honeycombs and your not yet using an afc or fuel tuning device of some sort, any dips in timing will indicate knock and thus timing being retarded (so long as your in the max airflow map - you should be if your running 17-18psi). Hope this helps,

Edit: should have read "Can't monitor knock"
 
That does, indeed help. I will certainly be investing in a logger in the near future so I can have a better understanding of what's happening, but I agree that at 17-18 psi, I'm probably seeing some ridiculous IDC's. I've decided not to go the AFC route simply because my chip upgrades trigger larger injectors like the stock ones and if it ran a tad rich up top (say 2% or so after deadtime adjustment which is pretty standard on a DSMChip and 550's), then I'd rather sacrifice a few horsepower and keep the motor safe than run it on the ragged edge and take chances.

Once again, thanks for the help and I'l be sure to report back once the new injectors and chip are installed on Friday.

Andy
 
450's, under the factory fuel curves for the peak values, which you should be on, should aim for a 9.5:1 AF in the topend, which means your 450's support 24.34lb/min for a IDC of 85% (the most id want to run injectors). If you truly maxed them out to 100% IDC, which isnt good to do, they will support 28.64lb/min under that same AF ratio. This AF ratio would assume you have no additional fuel corrections over the factory settings, which I assume you havent changed with your chip (perhaps I'm wrong). 28lb/min is easily overdone on that turbo, so you could very well be maxing those injectors out at that point, running damn close if not at 100% IDC. If your injectors do in fact hit 100% IDC, and you are attempting to run 9.5:1 factory fueling, this might not necessarily be an instant cause for alarm, as 9.5:1 is quite rich, and you have a good buffer zone there, as far as safety of your motor is concerned. At 100% IDC your injectors would be at their peak flow, however airflow could be increasing, causing the AF to lean out, however, at an AF of 11:1 your injectors are able to support 33.16lb/min, which is just 3lbs/min shy of the peak that youll ever see from that turbo even with full supporting mods.

I am not saying this, to cause you to stick with the injectors, as I dont believe you should, and I believe I proved there that you are pretty much most definately maxing them out, however I listed those figures to show you that you arent necessarily dangerously in the red, but likely at absolute worst somewhere in the 10.5-11:1 AF ratio with your IDC stuck at 100% (trying to flow more than 100% if it had its way). If you are running a small 16g, then your 550's will just barely squeek by on pump gas if you ever truly max out that turbo's abilities. Dave was right in having you get them. Personally however I would have gone with even larger injectors, something in the 650 or so range, just to cause the injectors to run at a very low IDC, and therefore have a longer life. Be sure to send your chip back to jeff to have it reprogrammed accordingly so that your timing values remain satisfactory, and you should be golden. The 190lph fuel pump is a very good match to your particular turbo, flowing 38lb/min at 15psi of boost for 9.5:1 AF, and 44.55lb/min at 11:1 AF at the same boost on stock wiring.
 
Thanks for jumping in on this and explaining IDC compared to maximum flow rate on the 16G. I think what it comes down to for me is my goals and also the limiting factors with my setup. With the 550's, I'd like to be able to run 18 psi on the street and 20-21 at the track with race fuel. I know that my next limiting factor will be the stock SMIC and this will likely be replaced with a Dejon sidemount (I want to retain a stock appearance and it fits into my budget well) or perhaps methanol injection on the existing sidemount.

In that light, since I have no desire to max out the 16G on pump, the 550's should work well enough for my purposes. Also, I did have Jeff burn me a new chip and he told me that he could dial in the FIC's so that I would still have zeroed AFC settings if I were ever to run one, which I have no plans to do. To address your other question regarding fuel maps, these were not adjusted in the chip so your calculations and theories should be right on with respect to A/F ratio.

I'll be installing shortly and providing feedback on how much the EGT's have come down at my current boost levels.

Thanks!

Andy
 
If thats truly where you'll stay then your injectors are well matched for your setup. With the chip burned you timing should stay as factory settings, so therefore you should be good to go. More power could be developed with additional timing as well as slightly leaned out AF ratios, however you can be assured that with the settings you are currently running with the new 550 chip, your AF should roughly correlate to a 9.5:1 AF or so in the topend, and your timing should peak to 16* at max if the injectors are perfectly dialed in, and Id assume with jeff's corrections they should be pretty close at worst. If you have a form of logger, you can watch this timing curve. With timing that low as well as an AF that rich, Id say you should be able to run some pretty solid boost settings. If you can get your hands on a logger you should be able to watch your timing curve as mentioned, which should roughly high 16* at most and plateau there above 6krpms, if you see timing drop below 16* you will know you're knocking and to back the boost off. I agree that your SMIC is a major restriction at this point, however upon it's replacement Id imagine you'll surprise yourself with the amount of boost you can run on a setup that doesnt have a comepletely crazy timing curve. I ran 21.5psi on my small 16g on pump gas with zero knock counts, with fuel support, 16* of timing, and the supporting mods (just bolt ons). Timing is the key to running high boost, which you should have under control.
 
As you mentioned, what makes this setup work is knowing and understanding the limitations of each component. I'm happy with the fact that I'll be able to run 18 psi safely and without issue and that I should also be able to see slightly more boost once the sidemount is upgraded to a unit that can cool the air charge more efficiently before heatsoaking. In putting this package together, I wanted something streetable and reliable that would plant me well from a first gear launch and be able to exploit most of the potential in the 16G (it's a big 16 as I found out from ExtremePSI by the way) without causing excessive breakage.

As it stands now, the injectors are in and all I'm waiting on is the chip. Once that's installed, I should be able to get a solid feel. And yes, a logger is definitely planned although I do have Jeff's chip set to monitor knock on the boost gauge.

Thanks for the help and also for information on timing. This isn't something I had correlated in my head, but now it makes perfect sense.

Andy
 
I received my chip today and after finishing the install and taking the car out for a ride, I can offer the following to all of you who answered my questions in this thread.

1. With Jeff's Stage III Chip installed, the car idles like a kitten on the 550's
2. EGT's at the top of my 3rd gear shift point (7200) are at 1540 instead of 1620+
3. EGT's now rise much more slowly than before in 3rd gear

The car pulls like a freight train at 18psi on pump where it'll stay unless I'm running something more potent at the track or until I upgrade the intercooler or add methanol injection.

On an interesting note, the FIC's seem to actually make a bit of noise at idle when I have the hood up. I never heard that with the stock injectors before, but I suppose that's what I get for not buying Denso.

Thanks again for the help everyone!

Andy
 
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