2G Engine heavily cutting out under boost. Check my logic?

[randman2011]

My 2g is running an HTA68 at 21 psi with MAP on Megasquirt.

The powertrain has been pretty reliable recently but about two weeks ago I drove the car and it started missing when the boost reached ~18 psi. Like constant misfires to the point where the car wouldn't really accelerate past 3500 RPM unless I kept the boost low. I took another drive and logged and saw nothing out of the ordinary in the data except some red herrings that I fixed. But when I drove it again, the threshold for this stuttering had dropped to 14 psi. Checked the plugs and they all looked really good except for some redness at the base of the ceramic insulator. The gaps were all at 0.028". Didn't find anything amiss but then on the next drive, the engine was now breaking up around 11 psi. These drives were all in consistently cool fall weather, which was a change.

So expecting a weak spark I dropped the gap down to 0.022" and the missing was nearly eliminated except for some one-off stutters high in the rev range only at max boost. So again I assumed that this was a rapidly weakening stock ignition system and started looking for replacements. But that successful drive was at summer temperatures again, so I wanted to confirm that this wasn't a cool temperature issue.

Well I drove the car in heavy snow yesterday and the behavior was the same as the warm weather: very impressive power with only one or two misses at the very high end. Do you agree that that says that I need to replace the coils and/or PTU? I haven't swapped the plugs yet mostly because I'm lazy, but also they have maybe 4000 miles on them. And if I upgrade to R35 coils, for example, the people that make those kits recommend iridium plugs so I didn't want to buy plugs twice.

In terms of cost, a set of genuine R35 coils isn't much higher than two Delphi OEM-replacement coils, NGK wires, and a WVE (no name?) PTU, and I can get off-brand R35 coils for less than just the cost of the two Delphi coils. So I'm not opposed to spending a bit more to get the whole COP setup even just for aesthetic reasons, but can someone check my work and make sure that I'm not missing something stupid? I'd rather not spend the money and effort going to COP/sequential spark if I don't have to.

EDIT: I should also add that the PTU is original and the coils are original from an EVO III. I have the original coils on a shelf and can swap them in to test, but even so the newest hardware that I have is 28 years old.

 

[jed344]

Closing the gap up helped quite a lot. Why not try a new set of plugs with the tighter gap? The plugs are cheap and i have seen plugs that had spark blow out continue to act up even when gap is closed vs new ones at that same gap. The stock ignition is more then capable even if some components may be aging for the power the car is making. You can test plug wire and coil resistance too if you want. I have only ever seen even ignition components out of spec either 1 just straight fail, or two start to show issues at far more power and boost.

 

[randman2011]

I actually went to the store yesterday to pick up new plugs because I figured I might as well, but they said they didn't have any even though the website said they had 16 in stock. So I'm just going to order some today, but yes I'm going to try that first.

Running the new plugs at the narrower gap seems like an odd strategy, though. If the rest of the ignition system suddenly can't jump the stock gap after 5 years of running it at or near this power level, that doesn't seem like something that I should ignore.

Thanks for reminding me about testing the coils, though. I completely forgot that that is an option! I'll check that when the new plugs go in.

Congrats on 1337 posts, btw!

 

[pauleyman]

Whaaaat...you mean we all don't have 2 dozen plugs in the toolbox?

 

[jed344]

I actually went to the store yesterday to pick up new plugs because I figured I might as well, but they said they didn't have any even though the website said they had 16 in stock. So I'm just going to order some today, but yes I'm going to try that first.

Running the new plugs at the narrower gap seems like an odd strategy, though. If the rest of the ignition system suddenly can't jump the stock gap after 5 years of running it at or near this power level, that doesn't seem like something that I should ignore.

Thanks for reminding me about testing the coils, though. I completely forgot that that is an option! I'll check that when the new plugs go in.

Congrats on 1337 posts, btw!

Plugs go bad. From personal experience though this usually is on e85 and more wild set ups, The gap opens up over time, it blows out spark, we tighten it back up. Still does. Grab new plugs go to same. Life is good. We change plugs very regularly.

 

[FIBA M - EC17PSE]

So based on what you said and your checks it does tally up to coils being a problem. Weahter its directly with them or a other wire/connector that works with them. The PTU needs a head sink and also the connects go lose over time so cable tie that down onto it more.

The loading part of the drive sputtering is a normal indication of coil packs as it comes and goes under load situations. But also something similar can be fuel filter if clogged but likely not to the same extent. If you got a wideband which im sure you would have that would tell you if its fuel and going lean under the loads or if its going rich then its coilpacks.

At least those are the two things i would personally check if it was my situation first and for.ost then check wiring and PTU.

 

[randman2011]

Finally an update. I got the standard 5534 BPR7ES and noted that they were all gapped at 0.028" from the factory despite 0.032" being the advertised spec. Maybe I should get a new set of feeler gauges?

Either way, the car runs flawlessly and I have finally closed all of the COP shopping tabs on my laptop. I'm not sure how they got into this condition given their age and serious lack of use, but they were degrading FAST and looked MUCH worse when I replaced them than they did when I checked them the week prior. Orange discoloration and visible cracks in the insulator on all four.

Now to fix everything else wrong with the car....

 

[FIBA M - EC17PSE]

Finally an update. I got the standard 5534 BPR7ES and noted that they were all gapped at 0.028" from the factory despite 0.032" being the advertised spec. Maybe I should get a new set of feeler gauges?

Either way, the car runs flawlessly and I have finally closed all of the COP shopping tabs on my laptop. I'm not sure how they got into this condition given their age and serious lack of use, but they were degrading FAST and looked MUCH worse when I replaced them than they did when I checked them the week prior. Orange discoloration and visible cracks in the insulator on all four.

Now to fix everything else wrong with the car....

So the older plugs were gapped wrong but new ones made the fix? You can check the feeler gauge with some calipers or mic but maybe just get some spark plug gapling tools with the pry on the ends. Some come with .28 as part of it which helps. I got one from craftsman i think it is.

 

[randman2011]

So the older plugs were gapped wrong but new ones made the fix? You can check the feeler gauge with some calipers or mic but maybe just get some spark plug gapling tools with the pry on the ends. Some come with .28 as part of it which helps. I got one from craftsman i think it is.

The old ones were set to 0.028 when I installed them in 2021. I dropped them down to 0.022 at the end of November for troubleshooting purposes. New ones are at 0.028 according to the same feeler gauges. So maybe my gauges have a problem and I've been running 0.032 this whole time, but either way, the car is running well now.

I'll pick up new gauges the next time I'm out.

 

[We're on Boost]

and a WVE (no name?) PTU

Glad your problem was just spark plugs!
I found the picture I wanted for talking about WVE, so I'm going to throw it in here in case you in the future need a new PTU or other such item.
Basically, I think that WVE is generally one of the better replacement parts brands. In your case with a 1998 GSX, the WVE PTU is the only one they show available at Rock Auto.
I wouldn't feel bad at all about buying one, and they only cost $84.

WVE is Wells Vehicle Electronics, an American Company that has absorbed various other brands over time and was itself acquired by NGK in 2015. So yup they are a brand of NGK now (Niterra).

Anyway there's a good chance that a WVE part will actually be made in Japan, and this goes back quite a few years.
For example, here is my pic of an Airtex/Wells ISC motor for 1g DSM, which I bought for a spare in 2017, and you can see on the box "Made in Japan". And on that same side of the box you can see "Wells Vehicle Electronics" at the bottom, below "Airtex".
These days, Wells is still based in Fond du Lac, Wisconsin. But 3 of their top executives are Japanese.
Standard Motor Products is another replacement parts brand that has been good for us usually, and the PTU in my 1990 is a Standard Motor Products, and it was Made In Japan.
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[danl]

The WVE ptu I got for my 1990 was in fact a factory NGK new old stock one that says Mitsubishi on the case.

Beware of where y’all buy spark plugs. There are china NGK ones on the market. I’ve seen two cases where they caused ignition issues. Luckily nobody has hurt a motor that I know of.