North American Turbocoupe Organization



Could I be detonating? (kinda long)
Noname
Guest
#1
I was wondering why I could never hit 18 psi steady all this time, so I did some changes. First I removed the BOV setup I had, and put back on the stock I/C. Then I changed the gillis valve around. Instead of running a vac line from the vac tree to the inlet of the gillis, I put in the T-fitting on the compressor housing, capped off one side of the T, and ran a vac line from the t-fitting, to the inlet end of the gillis. Then I ran the other vac line to the outlet to the WGA. So now I have the vac lines as short as possible. I checked timing and it is still set at 10 BTDC. I recently changed the d-cap, rotor, plug wires. Changed plugs 10k miles ago (I can't remember what the gap was, I guess I set it what the little sticker says on the fan shroud.

I also, just filled up on 93 octane fuel, and added a bottle of Crown Octane Booster.

After I hooked up the gillis, I checked a lot of the vac lines and made sure they were tightened down. I did NOT change the EGR emission hoses, the main I/C vac hose, or the vac hoses that run through the left side of the body. I never changed those little vac filters that are in the main I/C vac line.

I have a boost gauge installed and at idle in nuetral, its about 18 Hg. vac. When riding along without throttle, it runs at about 20/21 Hg. vac.

WHen I did the gillis test, I ran it with about 4-5 threads showing and got like 14/15 psi. I slowly tightened it in, but it wasn't going anywhere hardly. I'm down to about 2 threads left, and I hit about 16 psi. It feels like it looses a couple psi boost. For example, in 2nd, when you floor it, it goes to about 16 psi, but then at the end of 2nd, at like 5000 RPM, it will be down to 15/14.

I started hearing detonation, well I THINK i did. I don't know for sure what detonation sounds like, but I heard this faint sound coming from up in the engine comparment, it almost sounded like peices of metal shaking, or something shaking. It wasn't very loud, and the car didn't do any type of bucking or anything. It's nothing you can feel from inside the car. Now I'm wondering if maybe the knock sensor THINKS it hears detonation, and is pulling timing out. Would this pull out boost too? I'm not using the BCS, but when the KS pulls out timing, will that pull out boost?? Or should the boost pressure stay the same no matter what kinda of the timing is pulled out?

I don't see how I could be detonating, everything seems to be normal, and with 93 octane plus octane booster, it seems impossible. What could lead to detonation? What could I check? EGR valve? I never pulled the codes, though I want to next week maybe. I'm afraid to pull out the KS and run it, because I don't wanna blown a head gasket or anything (eventhough I ran with the KS disconnected for awhile). The turbo is still the stock IHI, which was driven with stock setup for 89k, then when I got I turned up the boost and ran it harder than the previous owner, could my turbo be going soon? Could the turbo be wore out, not be able to put out 18 psi (it has 105k miles on it). Someone help! What should I check and what affects detonation?

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1988 TurboCoupe - 5 Speed
5"x8" K&N / Cold Air Intake, Gillis Valve @ 18 psi, HKS Super Sequential BOV, 3" DP, 3" Cat, Dual 2.5" UltraFlos, Centerforce Dual Friction Clutch, Pro 5.0 Shifter, Autometer Boost/Vac & Air/Fuel Gauges
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Pete D Offline
Administrator
#2
Those round plastic things in some vacuum lines are not filters, they are flow control valves. They may let vacuum flow but not boost.

Detonation is often described as the sound of BBs (BB gun) rattling in a can.
It can be caused by too hot an engine (low coolant, improper timing) Too hot charge air (no intercooler, intercooler heat soaked, compressor operating in an inefficient area and thereby heating the charge air too much) A/F too lean (faulty sensors - several possibilities, vacuum leaks, weak fuel pump, insufficient fuel pressure, clogged fuel filter, too much ignition timing or too little octane, hot spots in the combustion chamber.

Since you don't have the factory BCS hooked up, the Gillis valve is the only contriol on boost you have.

Do your boost check in 4 or 5th. 2nd gear is not good as it doesn't load the engine enough and you are into 3 quickly.

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NATO Member
88 TC X 2, 86 SVO, Main TC with K&N, 3"DP to 2.5"duals through Dynamax, Ric valve at 17+ and disconnected KS. Elite Bodega 16" chrome wheels. Autometer pod w/ A/F and Vac/boost gauges.140 mph Motorsports Speedo New engine: Total Seal rings and TRW pistons, ported and polished head w/ cc'd chambers,1.59"exhausts, SS valves, gutted upper, knife edged lower, A-230 cam, Race Engineering Adj Cam Sprocket, Crowlers, ARP head studs, and rod bolts. Walbro 255 HP pump and Kirban adj FPR, T-3. Centerforce II, KB subs and jack rails.

[This message has been edited by Pete D (edited 03-24-2002).]
Pete Dunham


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Noname
Guest
#3
Yea, a couple people keep telling me I shouldn't worry about having different boost levels in the first couple of gears, just worry about the last couple gears. It just frustrates the shit outta when someone else with the same year turbo coupe can hit 18 psi in all gears, but then I hvae a different boost level in every gear...

I'm still wondering how I was detonating (if this was detonation) running in normal conditions with high octane gas..
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SteveX82 Offline
Posting Freak
#4
Quote:Originally posted by dm22:
just frustrates the shit outta when someone else with the same year turbo coupe can hit 18 psi in all gears, but then I hvae a different boost level in every gear...

I'm still wondering how I was detonating (if this was detonation) running in normal conditions with high octane gas..

I don't know of anybody who can buzz 18psi in first or second gear and still keep the boost levels safely around 17-18 in the upper gears with just a mechanical boost control valve. You'd need some sort of electronic boost control to manage boost levels that precisely.

I've also been having occasional problems with detonation and am also stumped as to what it could be. What does your A/F gauge read once you get into boost in the upper gears? Also, have you tried checking your fuel pressure yet?

[This message has been edited by SteveX82 (edited 03-25-2002).]
Estoril blue 1987 TC 5spd, 148k mi, a237, Bailey BOV, spec stg3 clutch, spearco FMIC, 50 trim t3/t4, 3" exhaust, Bamafuel, LM1, 55pph
Best 1/4 mile: 12.31 @ 110mph on 25psi
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SteveX82 Offline
Posting Freak
#5
double post..

[This message has been edited by SteveX82 (edited 03-25-2002).]
Estoril blue 1987 TC 5spd, 148k mi, a237, Bailey BOV, spec stg3 clutch, spearco FMIC, 50 trim t3/t4, 3" exhaust, Bamafuel, LM1, 55pph
Best 1/4 mile: 12.31 @ 110mph on 25psi
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Jeff K Offline
Administrator
#6
I hit a rock solid 20 psi in second, thrid, fourth, fifth. Even in first, I just hit 20 psi right when shifting to second.

I have a Dawes valve, which is functionally the same as a Gillis. I have it connected to the T on the turbo BUT, I have the T fitting orifaces drilled out WAY big. If you look at the T, you will see ALL the orifaces are quite small, which may have something to do with your problem. I use the second branch of the T fitting for another purpose, but for all intents and purposes, it is blocked off.

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 00 Windstar (wifes vehicle)

[This message has been edited by Jeff K (edited 03-25-2002).]
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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segfaultxr7 Offline
Posting Freak
#7
Looks like the TCs that can maintain full boost in all gears are equipped with T3s. I thought Jeff's 88 might be the exception until I saw his sig. IMO, the IHI is too small to keep the intake at full pressure when the engine is running at 4000+ rpm. Mine (with Gillis valve) drops a few PSI in first and second as well.
88 TC 5-speed
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Dan E Offline
Posting Freak
#8
With my T3 and Gillis I am able to hit 18 pounds in all gears too...

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Dan Eaves
88TC 5spd, Crower 5.5" Sportsman Rods, Short Wiseco Pistons bored .030" Over, Ported Head with Polished Combustion Chambers, Gutted & Polished Upper, Ported & Polished Lower, Polished T/B, Ported E6, SVO T3 .63AR Turbo, Bosch Bypass Valve, 3" DP w/No Cat, 2 1/2" DynoMax single cat back w/DynoMax Super Turbo Muffler, RR Cam, K&N in Fenderwell, Gillis Boost Valve, Centerforce I Clutch, Removed A/C, Polished Wheels, Polished Valve Cover, Polished Crank and W/P Pulleys, Walbro 255LPH HP Pump, Kirban Adj FPR, and the DAMN Heater Core is new too !

NATO MEMBER (Vice Chairman...if it's a vice...I deal with it)
Dan Eaves
88TC 5spd Vermillion Red, Polished...everything...
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Noname
Guest
#9
When I boost up, the a/f gauge reads the 3rd light on rich, and when you get higher in rpm, it goes to about the 4th light.

Today, when I floored it in 5th, I started hearing the car make a wierd noise almost like something is leaking out, but the boost doesn't jump down or anything, it very slowly was falling down, then when I let off throttle, i heard this sound, almost sounded like the car just sneezed. I thought it was this new K&N making those suction noises, but it just seems too loud to be the K&N. I'm suspecting a vac leak, almost like when my I/C hose was split.

In 2nd, I floored it, it boost up to about 16 psi, then by the time I got to 4500-5000 RPM, the boost was at 14/15, then when I let off throttle I heard the "chhhh" sneeze type noise again. When I get off work, I'm gonna look for more leaks.
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Dan E Offline
Posting Freak
#10
Quote:Originally posted by dm22:
I'm suspecting a vac leak, almost like when my I/C hose was split.

Did you replace the IC hose ? If not, I would have to belive that's your problem(s). Check both the hose under the IC and the hose to the Throttle Body.

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Dan Eaves
88TC 5spd, Crower 5.5" Sportsman Rods, Short Wiseco Pistons bored .030" Over, Ported Head with Polished Combustion Chambers, Gutted & Polished Upper, Ported & Polished Lower, Polished T/B, Ported E6, SVO T3 .63AR Turbo, Bosch Bypass Valve, 3" DP w/No Cat, 2 1/2" DynoMax single cat back w/DynoMax Super Turbo Muffler, RR Cam, K&N in Fenderwell, Gillis Boost Valve, Centerforce I Clutch, Removed A/C, Polished Wheels, Polished Valve Cover, Polished Crank and W/P Pulleys, Walbro 255LPH HP Pump, Kirban Adj FPR, and the DAMN Heater Core is new too !

NATO MEMBER (Vice Chairman...if it's a vice...I deal with it)
Dan Eaves
88TC 5spd Vermillion Red, Polished...everything...
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