Car running rough

Tiny
REEDBONE
  • MEMBER
  • 1990 MAZDA MIATA
  • 202,000 MILES
I have a 90 mazda miata and it runs really and when I stomp on gas it boggs down and then the rpms go up and when I put In gear I have to raise the rpms to like 4000 to get it to move without shutting off and I tested maf and injectors it also gets really bad gas milage amy ideas I thought maybe it was fuel pump any help would be greatly appreciated
Saturday, June 23rd, 2012 AT 12:23 AM

13 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
How did you test the mass air flow. What was the voltage at idle and at 2500?

Check fuel pressure.

Check the cat converter for back pressure.

Roy
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Saturday, June 23rd, 2012 AT 12:34 AM
Tiny
REEDBONE
  • MEMBER
  • 75 POSTS
I unplugged maf while running at when I did it ran different and I dont have fuel gauge and I checked cat converter and I beat it out thought it was clogged and it wasnt
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Saturday, June 23rd, 2012 AT 12:38 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Unplugging the mass air flow is not a test. It needs to be monitored with a scan tool for voltages and glitches.

The cat gets checked with a back pressure gauge to see if it bad.

Get some help here from someone familiar with this kind of testing

Roy
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Saturday, June 23rd, 2012 AT 12:45 AM
Tiny
REEDBONE
  • MEMBER
  • 75 POSTS
How would I scan the maf with a regular meter?
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Saturday, June 23rd, 2012 AT 12:50 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Most meters are not fast enough. Thats why you need a scanner.

Roy
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Saturday, June 23rd, 2012 AT 12:54 AM
Tiny
REEDBONE
  • MEMBER
  • 75 POSTS
Would there be any other possible things it could be if fuel pump looses pressire would it make it run like that
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Saturday, June 23rd, 2012 AT 12:57 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
It could but you need to monitor the o2 sensor to see what is happening. The simple days of testing is gone. You need special tools for todays car. It is cheaper to have someone check it and give you the exact failure than you throwing parts at it that dont fix it.

Roy
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Saturday, June 23rd, 2012 AT 1:03 AM
Tiny
REEDBONE
  • MEMBER
  • 75 POSTS
I thought it had to be a 96 or new with the scanners they have
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Saturday, June 23rd, 2012 AT 1:05 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Scanners go back to the 80's when computer controls started. That was called obd1. 96 and up are obd2

Roy
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Saturday, June 23rd, 2012 AT 1:18 AM
Tiny
REEDBONE
  • MEMBER
  • 75 POSTS
Ya well ive asked around and most people have gotten rid of obd 1 &do u know of a good shop to take it to
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Saturday, June 23rd, 2012 AT 1:20 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
What area? I am in Pa. And familiar with Phila and harrisburg area.

Roy
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Saturday, June 23rd, 2012 AT 1:23 AM
Tiny
REEDBONE
  • MEMBER
  • 75 POSTS
Brunswick georgia like meinekin or a dealership
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Saturday, June 23rd, 2012 AT 1:31 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Wish I could help but no info I can provide. Good luck

Roy
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Saturday, June 23rd, 2012 AT 1:34 AM

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