PCM Diagnostics & Tuning HP Tuners | Holley | Diablo

LS1 RX7 not running right

Thread Tools
 
Search this Thread
 
Old Jun 24, 2007 | 07:47 PM
  #1  
Sabre002's Avatar
Thread Starter
12 Second Club
iTrader: (7)
 
Joined: May 2004
Posts: 543
Likes: 1
From: Columbia, SC
Default LS1 RX7 not running right

ok I just want to bounce this off some other people.

I got my car some what running I should say, with a base tune from my tunner but it will just not stay running when I touch the throttle it has no response at all and then it will die. I'm throwing one code witch is a P0102 Mass Air Flow (MAF) Circuit Low Input. Now I did do something a little different with my MAF in how it is mounted in a 4" pipe but I dont see this being the proublem unless I damaged it when I was moding it.

here is how I have it mounted

But even if the MAF is damaged I just dont see it as the reason the car is running so bad or not wanting to run. It will fire and idle but then if I touch the throttle it will die and it had to start agian. The tune sould be able to get me up and running but there is no way to drive it like this. and I pulled a plug today it you smell nothing but fuel so I belive it is way rich. Does anyone have any ideas as what to look for I'm thinking I need to take the ECM back to the tuner for him to have a 2nd try at it.

Mods on the motor are
Comp cam .589/.589 236/236 112LSA
1 7/8 headers
4" custom CIA

http://www.obd-codes.com/trouble_cod...-low-input.php
Reply
Old Jun 24, 2007 | 08:28 PM
  #2  
sciff5's Avatar
11 Second Club
20 Year Member
Photogenic
iTrader: (1)
 
Joined: Jan 2006
Posts: 1,308
Likes: 1
Default

I would like to know if the maf works like this. If so, this is deff what I would like to do with my Ls1 FC.

Let me know how it works out

-Josh
Reply
Old Jun 24, 2007 | 08:39 PM
  #3  
ZV8's Avatar
ZV8
12 Second Club
iTrader: (2)
 
Joined: Oct 2006
Posts: 218
Likes: 0
From: Las Vegas, NV
Default

Im not sure what size the stock MAF sits in but the stock MAF is designed to sense the amount of air in a stock sized port, so if you make it wider then it will read differently so your gona have to tune it a little different. did you try cleaning the MAF? try that if not, check for vacuum leaks too. Did you take the car to get tuned or just do a mail order tune or what?
Reply
Old Jun 24, 2007 | 10:20 PM
  #4  
rosey's Avatar
Staging Lane
iTrader: (13)
 
Joined: Mar 2006
Posts: 91
Likes: 0
From: Madison, WI
Default

I'm pretty sure running the maf like that will throw the calibration way off, hell, adding a lid on an f-body is enough to screw with it a bit. I'm sure you know how the maf works, so its pretty obvious that completely changing the flow characteristics through it will mess it up.

When I first got my ls1 running it ran pretty lean, it was cutting out at part throttle and that is just with bolt ons and a stock maf. A wideband is really useful to help you figure out what exactly is going on, when I realized how lean my car was running, I turned off the MAF and added like 5-10% on the VE table and the car ran waayy better, just a bit rich....cleaned up the VE table and it runs great. I've since turn the maf back on, and recalibrated it, now she runs like a champ. I'd think you'll very likely need to recalibrate your maf, but you'll probably want to get you VEs in line first.
Reply
Old Jun 24, 2007 | 11:26 PM
  #5  
Nick Williams's Avatar
Launching!
iTrader: (2)
 
Joined: Dec 2002
Posts: 225
Likes: 0
From: Mooresville, NC
Default

Josh,

Try unpugging the MAF and see if it will start. Give me a call tomorrow. Most likely something is wrong in the wiring or the MAF is bad.

Nick
Reply
Old Jun 25, 2007 | 02:48 AM
  #6  
SpdFrk1990's Avatar
TECH Addict
iTrader: (6)
 
Joined: May 2005
Posts: 2,571
Likes: 1
From: Cincinnati
Default

Yeh ill have to go with it wont run right like that. Its not made to meter air in a pipe that big. Just get a speed density tune and be gone with it.
Reply
Old Jun 25, 2007 | 02:49 AM
  #7  
SpdFrk1990's Avatar
TECH Addict
iTrader: (6)
 
Joined: May 2005
Posts: 2,571
Likes: 1
From: Cincinnati
Default

Yeh ill have to go with it wont run right like that. Its not made to meter air in a pipe that big. Just get a speed density tune and be done with it.
Reply
Old Jun 25, 2007 | 09:58 AM
  #8  
wait4me's Avatar
TECH Addict
iTrader: (10)
 
Joined: Feb 2003
Posts: 2,961
Likes: 2
From: warsaw, in
Default

That meter definatly wont work right. Also at High volocity, i would say that it will break and get sucked into your engine at wot. There will be alot of force on the electronics and with no support of it on the bottom on your picture will create alot of leverage to make it break even easier.

A meter has to be set up EXACTLY for the enclosure that the electronics are in. You cant just change the houseing and expect it to Count the accurate amount of airflow.

It will not work.
Reply
LS1 Tech Stories

The Best V8 Stories One Small Block at Time

story-0

Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

 Pouria Savadkouei
story-1

Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

 Verdad Gallardo
story-2

7 Most Reliable High-Performance Engines GM Has Ever Built

 Verdad Gallardo
story-3

Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

 Verdad Gallardo
story-4

6 Common C5 Corvette Failures and What's Involved In Repairing Them

 Pouria Savadkouei
story-5

Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

 Verdad Gallardo
story-6

Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

 Pouria Savadkouei
story-7

Top 10 Most Powerful Chevy Trucks Ever Made!

 
story-8

Hennessey's New Supercharged Silverado ZR2 Has 700 HP

 Verdad Gallardo
story-9

Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

 Verdad Gallardo
Old Jun 26, 2007 | 01:25 AM
  #9  
Sabre002's Avatar
Thread Starter
12 Second Club
iTrader: (7)
 
Joined: May 2004
Posts: 543
Likes: 1
From: Columbia, SC
Default

I relized that changing it with out tunning will not work but, I would also like to see if this will work with some tunning. How else do you explane the turbo cars with MAF setups working?


Thanks nick I will give you a call tuesday.
Reply
Old Jun 26, 2007 | 09:24 AM
  #10  
LS1-450's Avatar
TECH Junkie
iTrader: (33)
 
Joined: Aug 2005
Posts: 3,783
Likes: 9
Default

MAF low input means that there is a problem with the reference voltage sent from the PCM (ECU) to the MAF. Check the voltage input wire w/ a voltage meter. The input voltage should be 5 volts. The PCM s sending a code because it's not 5 volts. You need to find out why. Either the MAF is bad, another or more than one other sensor on the same reference voltage circuit can also be causing the problem. There could be a wiring issues....etc..
Reply
Old Jun 26, 2007 | 03:05 PM
  #11  
Sabre002's Avatar
Thread Starter
12 Second Club
iTrader: (7)
 
Joined: May 2004
Posts: 543
Likes: 1
From: Columbia, SC
Default

Here is something I left out. when I first put my fuel system together it got pressure tested to 100PSI casue the adjuster was cranked down on the fuel pressure regulator. So the question is would that mess up the injectors?
Reply
Old Jun 26, 2007 | 03:38 PM
  #12  
NoGo's Avatar
TECH Addict
20 Year Member
Photogenic
Photoriffic
iTrader: (2)
 
Joined: Jan 2002
Posts: 2,815
Likes: 110
From: Mass
Default

Personally, I wouldn't use the MAF in that configuration. You can get them to throw codes on a stock LS1 just by turning the MAF sideways...

I don't think 100 PSI would harm your injectors while they are closed. If you are worried about it flip the injector fuel rail over (with the injectors and fue lines connected) and turn the key on to prime the pump. If you don't see anything oozing out you are all good.

If you have to squeeze the MAF in such a rotten spot, just remove it and go to a SD tune.
Reply
Old Jun 26, 2007 | 08:39 PM
  #13  
2002_Z28_Six_Speed's Avatar
TECH Veteran
iTrader: (19)
 
Joined: Aug 2005
Posts: 4,538
Likes: 1
From: Wash, DC
Default

Do you got a wideband?? I know what is happening.

Do yourself a favor and just don't use the MAF. The way you have the MAF it is making your car too lean. Don't run it like that. Eliminate the codes from displaying a MIL, but don't disable them. Then, tune the car.
Reply
Old Jun 26, 2007 | 09:38 PM
  #14  
Sabre002's Avatar
Thread Starter
12 Second Club
iTrader: (7)
 
Joined: May 2004
Posts: 543
Likes: 1
From: Columbia, SC
Default

The car is deff not lean. it is soaking the plugs with gas it is so rich. I think everyone is just hung up on my MAF setup, it runs the same with it pluged in or unpluged.
Reply
Old Jun 30, 2007 | 04:32 PM
  #15  
Sabre002's Avatar
Thread Starter
12 Second Club
iTrader: (7)
 
Joined: May 2004
Posts: 543
Likes: 1
From: Columbia, SC
Default

ok I got a stock MAF on it now and it does run better. But the car is still so rich that is is fouling plugs, I'm thinking that if I drop the fuel pressure some will that help to lean it out for the moment so I can run it to get it up to temp to test the fans and make sure the stat will open. I'm not looking for a permenent fix I just want something I can do right now with out tunning software to keep it running ok.
Reply




All times are GMT -5. The time now is 08:59 AM.

story-0
Topdon ONE vs. Artidiag 800 BT2: Which is the Diagnostic Tablet For You?

Slideshow: We take a close look at the ONE and Artidiag 800BT2 diagnostic tools from Topdon and the reasons to buy one over the other.

By Pouria Savadkouei | 2026-05-28 11:05:11


VIEW MORE
story-1
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine

Slideshow: The controversial Ferrari F6 swaps its original flat-12 for a Corvette Z06-derived LT4 V8 and sends power to four rear wheels through a custom-built drivetrain.

By Verdad Gallardo | 2026-05-26 18:23:54


VIEW MORE
story-2
7 Most Reliable High-Performance Engines GM Has Ever Built

Slideshow:These GM engines didn't just make huge power, they survived abuse, boost, track days, and six-digit mileage with a reputation for refusing to quit.

By Verdad Gallardo | 2026-05-21 16:45:27


VIEW MORE
story-3
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin

Slideshow: This heavily modified 1971 Camaro mixes classic muscle car styling with a fifth-generation Camaro interior and modern LS3 power.

By Verdad Gallardo | 2026-05-12 18:06:42


VIEW MORE
story-4
6 Common C5 Corvette Failures and What's Involved In Repairing Them

Slideshow: From wobbling harmonic balancers to failed EBCMs, these are the issues that define long-term C5 ownership and what repairs typically involve.

By Pouria Savadkouei | 2026-05-07 18:44:57


VIEW MORE
story-5
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph

Slideshow: A modern Camaro transformed into a retro icon, this limited-run "Bandit" build blends nostalgia with brute force in a way few revivals manage.

By Verdad Gallardo | 2026-04-21 13:57:02


VIEW MORE
story-6
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked

Slideshow: Cadillac didn't just crash the high-performance luxury vehicle party, it showed up loud, supercharged, and occasionally a little unhinged...

By Pouria Savadkouei | 2026-04-16 10:05:15


VIEW MORE
story-7
Top 10 Most Powerful Chevy Trucks Ever Made!

Slideshow: Top ten most powerful Chevy trucks ever made

By | 2026-03-25 09:22:26


VIEW MORE
story-8
Hennessey's New Supercharged Silverado ZR2 Has 700 HP

Slideshow: Hennessey has turned the Silverado ZR2 into a 700-hp off-road monster with supercharged V8 power and a limited production run.

By Verdad Gallardo | 2026-03-24 18:57:52


VIEW MORE
story-9
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes

Slideshow: A one-off sports car that looks like a vintage Italian exotic-but hides a C6 Corvette underneath-just sold for the price of a new mid-engine Corvette.

By Verdad Gallardo | 2026-03-23 18:53:41


VIEW MORE