RestoTII

My 87TII decided to give me problems and detonation is something that's been suggested for me to check out. thing is, if it's detonating, what can I do? I don't want to mess with timing and stuff like that if it's going to mke it worse, and I don't want to blindly adjust stuff and hope it helps, so what should I try? thanks

Brian_TII

What is your car doing wrong? What makes you think it's detonation?

RestoTII

My other thread about what it's doing
https://www.rx7club.com/forum/showth...threadid=56739

hypntyz7

Ever been in an FC with no shifter bushings and heard the thing lightly rattle like youre dragging a tin can down the road? Thats sorta what detonation sounds like from in the car. Like a shifter or something rattling. Very faint if you have an exhaust on the car.

IF you think its detonation, act NOW. 10 runs or less of detonation can and will kill the engine. Either keep your foot partially out of it(control boost to halfway or less) or retard the timing until you have time to look into it properly. Timing is adjustable inseconds, loosen the 10mm nut on the CAS and turn it CCW to retard. Youll be able to see the shiny spot once its moved, which was the stock setting, so later you can return it even if you dont have a timing light which I recomend. Retarding the timing a few mm(about 1mm on the CAS roughly equals 5* on the crank) will give youa slight bit less power but a larger safety margin overall for running boost, especially higher than stock boost.

This is not meant as a fix, but a safeguard temporarily.

RestoTII

thanks. I'll see what i can do here between homework and exams and papers. Figures I'd start having a problem right before I get ready to go home.

RestoTII

Is it just my thinking, or will the car just have detonation problems when boost starts? If I unplug the FCD and keep my foot off the gas, would that do anything? Also, would octane booster help it out? I need to make a 120 mile trip home this friday for spring break and that's where the garage is, so I'm just looking for something to get it home without it dying before I troubleshoot too much. Thanks

hypntyz7

As long as you dont hit anything above stock boost it should not detonate unles you got some really shitty pump gas. Highway driving will be fine. If I were you Id run out ALL the gas you currently have then fill up with 93.

RestoTII

i run nothing but 93.... i was thinking the same, till I realized, I just filled up with 93 on Friday and had probs saturday. Hopefully I got some bad *** gas. I'll go cruise and kill the tank at low/no boost and refill. If that doesn't help anything, I'll give octace booster a shot before I touch the timing. I don't have a light here, so adjustments would be very crude. Thanks again, and if anyone else has ideas about what i can do, feel free to toss them in.

RestoTII

ok, I just ran it down to 1/4 tank and refilled with 94 octane. I ran it for a little while longer to make sure everything settled and was mixed and through the system, then got on it once and had no loud rattling like before. Hopefully that means I just had bad gas there, but I still want to look more into it, cause it's acting strange lately

Poindexter10thae

iTrader: (2)

Do you have an A/F ratio gauge? I would highly suggest you get one, that would answer your detonation questions simply by looking at the gauge when you hear that sound. Just do what hypntyz7 said, run stock boost with high octance gas and you will not detonate, as long as there isnt something else awry................

Poindexter10thae

iTrader: (2)

Just read your other post, Autometer makes an A/F ratio gauge that is VERY affordable, 49.95, you can get it from summitracing.com. I find that it does its job well on a daily driven 7

RestoTII

funny you mention the gauge... I just made a post about getting one, but no one's replied there
https://www.rx7club.com/forum/showth...threadid=57175

Scott 89t2

A/F gauge won't help. pinging is caused by heat. you can have correct A/F mix and still ping. an exhaust temp gauge is much more usefull.

ponykiller

before any hard driving, or a long trip, pour a can of toluene into the gas tank. It raises the octane by more than 5 points, while octane booster raises it by about 1/2 of a point. They also cost the same.
oh yeah, you buy toluene at a hardware store, but be VERY CAREFUL with it. DON'T breath it/touch it. It is carcinogenic and once it enters your body, it NEVER leaves. It goes to your bones and builds up in the marrow. Be EXTREMELY careful with it.

ok, i'm doing being a mother, but the stuff works great, especially if you know you are gonna be rough on your car.


Kris

RestoTII

First, about the pinging and EGT. I was under the impression that Exhaust gas temps were a direct result of the a/f mix. Stoich produces one temp, rich is cooler, and lean is hotter. Problem with an EGT is that heat transfer takes time, so if I'm running lean at one point, it'll take a little while for the gauge to respond. Also, I can't see pinging happening at stoich since the mix would create a certain temp flame (sort of like the adiabatic flame temperatures I spent so long calculating last semester).
Next about the toluene... how much is safe to add? I might pick some up to make sure it's cool for tha 120 mile trip home. And that stuff's safe for injectors, fuel filter, etc? Thanks

UniqueTII

Did you have oxygenated gas in there? My TII always detonates like crazy with oxygenated gas...it'll say whether it is or not on the pump.

hypntyz7

resto t2...youire only seeig half the picture...

you can have perfect a/f ratio, but if you get some bad fuel, or just whatever, you can still detonate. Say you have a perfect a/f ratio, but you advance the timing. We all know advanced timing makes more power and makes an engine ru hotter as well. This brings it closer to detonation. SO your a/f gage could read stoich but your egt would be super high. Just an example. There are 2 sides to teh coin.

Wankel7

Water injection can be a nice way to eliminate that problem.

RestoTII

of course I'm looking for cheap ways to fix it, since the guy before me was a real dick, I'm not sure how long the engine has, and I don't want to build on a shaky foundation. Plus, I've got no job, so my tax refund's going for this project. Thanks for the suggestions guys, and I see what you mean hypntyz

ponykiller

add an entire can of the toluene to a full gas tank (about two quarts, more is better), it is fine for all the engine components. It is much better than octane booster.
Water injection is also something to consider. I have read quite a bit about it and I believe I will be installing a system with my hybrid turbo.

Kris

sinfestboy

I have to jump in, there is a slight chance I may make myself sound dumm, but o well. I dont want to see you wasting money...
the only use for water injector is to prevent knocking. it costs too much for how much it helps, it would be much smarter to simply turn boost down untill you can afford an IC. here are a couple quotes from "Maximum Boost", a book by Corky bell, which is very good
"It has little place in a properly concived turbo system"
"To stake the margin of safety of a turbocharged vehicle on an inherently unreliable device is an idea whose time has long since passed. RIP."
"All things considered, you would be far ahead never to have heard of a water injector."

and after doing a little more reading, I agree. Just turn the boost down a little, and get an IC setup ASAP.

Wankel7

Detonation = Knocking. They are the same thing. If he wants to keep his setup and current boost levels a water injection system would makeup for the short comings of the current system. Either a spray into the intake air or onto the outside of the intercooler.

Granted, it would better now to turn the boost down. But, a water injection system from Aquamist would be cheaper than a Greddy or HKS FMIC. Unless it was a good ol DIY IC.

James

sinfestboy

yeah, but water injection wont be as reliable as a decent IC cystem. and remember, for the amount of money he is spending on the water injection system, he could just get an IC system that much sooner.

RestoTII

well the problems seem like they're sticking around, with pulses at idle and rough pick up when pulling out. Seems like there might even be an odd sound from the rear rotor.... so I'm hoping the engine isn't dying, but something tells me the rear rotor is taking a **** on me

sinfestboy

here's a refreshing idea:

Nitrous.

the new NOSzle (Holley, Nitrous oxide systems, aka NOS) wouldnt reduce flow anywhere. it cools the air (because nitrous is coooold), and such stops detonation, and it significantly increases power. think about it, its perfect for the situation. It stops your detonation, gives you power when you need it (not taking power away, like downing boost), and it impresses girls who saw FnF (joke). I think I just actually helped someone....