Power falls off at 6800 RPM 18 psi 2871R - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


DIY Turbo Discussion greddy on a 1.8? homebrew kit?

Reply
 
 
 
LinkBack Thread Tools
Old 03-25-2012, 09:31 AM   #1
Newb
Thread Starter
iTrader: (2)
 
Join Date: Nov 2007
Posts: 32
Total Cats: 0
Default Power falls off at 6800 RPM 18 psi 2871R

My car seems to roll off power hard after 6800 rpm in low boost (10 psi) and high boost (18 psi) Is this a problem with the stock igniter? Does anyone else have problems dropping off power at this RPM?

92 Miata
Link ECU (rev limit set at 7200)
E-85
850cc injectors
Built 94 bottom end / 99 head and intake manifold
GT2871R
Stock igniter
Toyota COP
~18 PSI

__________________________________________________ _____
Data Log Lab MAP File
File Created: 06-Mar-2012 14:41

015 088 072 254 040 211 020 022 017 088 022 034 000 035 035 052

015 010 049 047 012 020 012 011 010 009 061 062 070 087 099 100

056 051 053 056 066 062 059 063 071 066 065 064 063 062 059 056
052 053 057 063 066 070 064 072 071 074 072 069 064 063 062 060
054 056 059 061 067 071 075 081 079 088 087 076 071 067 066 064
059 061 063 065 069 082 080 101 100 102 098 097 097 093 088 085
067 069 071 073 076 087 105 108 111 113 114 114 111 105 100 098
006 005 081 083 085 094 101 106 105 108 110 107 099 094 090 089

040 040 052 077 081 120 124 127 125 120 118 121 124 126 128 130
040 040 064 104 114 118 121 123 122 112 107 109 112 116 120 124
040 040 080 098 104 106 108 104 100 098 100 102 104 106 110 114
040 040 077 094 100 098 090 081 073 070 074 080 086 091 095 099
040 040 060 080 085 078 068 059 052 050 053 057 062 068 074 080
000 000 045 052 055 053 046 038 033 030 038 046 051 056 062 066

003 194 022 050 102 254 254 255 254 254 254 254 254 254 254 254
000 084 049 032 008 100 080 150 015 030 016 025 026 035 030 032

Engine Size: 1.8
Chip Date: 2001-09-18
Chip Version: 2
Atmospheric Pressure: 100
Attached Thumbnails
Power falls off at 6800 RPM 18 psi 2871R-miata-powerloss-v2.jpg  
spestis is offline   Reply With Quote
Old 03-25-2012, 12:47 PM   #2
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

Wow that is quite significant. In for the answer.
Faeflora is offline   Reply With Quote
Old 03-25-2012, 12:56 PM   #3
Elite Member
iTrader: (6)
 
Join Date: Nov 2007
Location: Southlake,Texas
Posts: 3,251
Total Cats: 17
Default

3'' Exhaust?
Bond is offline   Reply With Quote
Old 03-25-2012, 01:43 PM   #4
Newb
Thread Starter
iTrader: (2)
 
Join Date: Nov 2007
Posts: 32
Total Cats: 0
Default

Yes, It has a full 3" exhaust. And a .68 a/r turbine housing. Also its a genuine garrett GT2871r.

http://www.stanlevine.com/Miata/Album8.htm
spestis is offline   Reply With Quote
Old 03-25-2012, 01:48 PM   #5
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,202
Total Cats: 2,584
Default

What are you using for boost control and where is it getting its signal?
18psi is offline   Reply With Quote
Old 03-25-2012, 02:03 PM   #6
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

Does it feel like power fails on the street too?
Faeflora is offline   Reply With Quote
Old 03-25-2012, 02:09 PM   #7
Newb
Thread Starter
iTrader: (2)
 
Join Date: Nov 2007
Posts: 32
Total Cats: 0
Default

I'm using a manual Hallman boost controller off the compressor housing. It does not feel like its falling off power on the street; however there is a lot going on ie. open wastegate, high rpm, just before I shift.
spestis is offline   Reply With Quote
Old 03-25-2012, 02:22 PM   #8
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

Post a log of a street pull with boost logged.
Faeflora is offline   Reply With Quote
Old 03-25-2012, 02:27 PM   #9
mkturbo.com
iTrader: (24)
 
shuiend's Avatar
 
Join Date: May 2006
Location: Charleston SC
Posts: 13,780
Total Cats: 1,106
Default

Quote:
Originally Posted by spestis View Post
Yes, It has a full 3" exhaust. And a .68 a/r turbine housing. Also its a genuine garrett GT2871r.

http://www.stanlevine.com/Miata/Album8.htm
Did you mean .64 A/R? Could you give us the exact model number for your turbo?
shuiend is offline   Reply With Quote
Old 03-25-2012, 02:38 PM   #10
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,202
Total Cats: 2,584
Default

run your boost line off the manifold and not the turbo.
18psi is offline   Reply With Quote
Old 03-25-2012, 06:20 PM   #11
Newb
Thread Starter
iTrader: (2)
 
Join Date: Nov 2007
Posts: 32
Total Cats: 0
Default

I don't think the drop in power is from a loss in boost. In the dyno chart you can see boost raise up as power falls off. More like there is some restriction in the system.
spestis is offline   Reply With Quote
Old 03-25-2012, 06:22 PM   #12
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

Quote:
Originally Posted by spestis View Post
I don't think the drop in power is from a loss in boost. In the dyno chart you can see boost raise up as power falls off. More like there is some restriction in the system.
Restriction as in you stuffed a melon in your plenum?
Faeflora is offline   Reply With Quote
Old 03-25-2012, 06:24 PM   #13
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,202
Total Cats: 2,584
Default

Doubt you're having weak spark with the toyota cops. And you'd get misfires/blowout if you did. Look at the boost curve: it sags a good bit then shoots up towards the very end: doesn't look good to me, even if that's not your torque taper problem.

what does your timing map look like?
18psi is offline   Reply With Quote
Old 03-25-2012, 06:56 PM   #14
Newb
Thread Starter
iTrader: (2)
 
Join Date: Nov 2007
Posts: 32
Total Cats: 0
Default

My thought was maybe the Link ecu and stock ignitor are having problems after 6800 rpm. You are correct if it was igntion I should feel the car break up.

Timing Chart Below KPA / RPM
Attached Thumbnails
Power falls off at 6800 RPM 18 psi 2871R-timing.jpg  

Last edited by spestis; 03-25-2012 at 09:07 PM.
spestis is offline   Reply With Quote
Old 03-25-2012, 07:17 PM   #15
Murderator
iTrader: (76)
 
18psi's Avatar
 
Join Date: Apr 2008
Posts: 36,202
Total Cats: 2,584
Default

well the timing is fairly ballsy, so its not the timing. lol
are you seriously running 30* @ 200 kpa or am I reading that wrong?
18psi is offline   Reply With Quote
Old 03-25-2012, 07:26 PM   #16
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,371
Total Cats: 1,332
Default

Are you using the factory ignitor AND the Toyota COPs in tandem? The Toyota coils have on-board ignitors.
Savington is offline   Reply With Quote
Old 03-25-2012, 09:09 PM   #17
Newb
Thread Starter
iTrader: (2)
 
Join Date: Nov 2007
Posts: 32
Total Cats: 0
Default

Good call, the chart was incorrect. I posted the correct timing chart above. I forgot my stock ignitor box was gutted. I have not worked on my car in around 3 years.
spestis is offline   Reply With Quote
Old 03-25-2012, 09:40 PM   #18
Junior Member
iTrader: (3)
 
Join Date: Oct 2010
Posts: 201
Total Cats: 2
Default

perhaps its too much timing up top. then again...ur making alot of power maybe its time to look into getting cams.
samwu8k is offline   Reply With Quote
Old 03-25-2012, 10:11 PM   #19
Elite Member
iTrader: (2)
 
Join Date: Jan 2007
Location: Los Angeles, CA
Posts: 8,782
Total Cats: 119
Default

Quote:
Originally Posted by samwu8k View Post
perhaps its too much timing up top. then again...ur making alot of power maybe its time to look into getting cams.

You are wrong.
Faeflora is offline   Reply With Quote
Old 04-04-2012, 01:02 PM   #20
Newb
Thread Starter
iTrader: (2)
 
Join Date: Nov 2007
Posts: 32
Total Cats: 0
Default

Update: I did find the problem. The dynos RPM numbers are off and the power drop signature is the Link ECU hitting the rev limit (at 7200 rpm). The Link drops the timing to 0 deg. just before the rev limit and that is why the power falls off. The dyno was off by several hundred RPM.
spestis is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 59 12-15-2017 09:00 PM
My solution for Oiltemp and Oilpressure input into Megasuirt (MS3) Zaphod MEGAsquirt 41 01-24-2016 01:25 PM
Back to Stock Part Out!! Turbo Parts, MS2 Enhanced 01-05, Suspension, and MOAR! StratoBlue1109 Miata parts for sale/trade 16 10-02-2015 10:39 AM
Low oil pressure after 1.8 swap and new turbo setup JesseTheNoob DIY Turbo Discussion 15 09-30-2015 03:44 PM
Are my coils failing? viriiguy General Miata Chat 5 09-28-2015 08:39 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 07:49 PM.