Compression Test Results

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fost9508

New Member

Aug 28, 2004

131

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Nov 16, 2004

#1

• Nov 16, 2004

• #1

I did a compression test on all eight of my cylinders the other day. The results seemed fairly high. I have an 88GT 5.0. All the tests are dry test.

EDIT: I guess formating does not carry over in the forum. the fist number is the cylinder, the second number is the compression on the first stroke, and the third number is the final compression reading after multiple strokes.

Cylinder # 1st Stroke (psi) Final (psi)
1 120 180
2 120 180
3 120 180
4 120 185
5 120 185
6 120 190
7 120 185
8 120 190

Let me know what you guys think.

Thanks

 

DMAN302

My mom says thanks for the pearl necklace.

Nov 8, 2003

2,120

2

59

windsor, Canada

Nov 16, 2004

#2

• Nov 16, 2004

• #2

perfect #, now start modding the car because you have plenty on life in her.

 

bgjohnson

Founding Member

Sep 1, 2002

963

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16

johnston,iowa

Nov 16, 2004

#3

• Nov 16, 2004

• #3

that's perfect man, and that's a dry test. woot!!

 

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fost9508

New Member

Aug 28, 2004

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Nov 16, 2004

#4

• Nov 16, 2004

• #4

Thanks for the input guys...that is reasuring, at least the block, rings, valve etc...are presumably in good condition. The car still runs like crap though. I think it has to do with the multitude of sensor in the damn thing. The next sensor I am going to check is the ECT. I have heard that sensor can be tied to poor gas mileage. The just seems a little slugish in all rpms except like 3500. After that sometimes it either hisitates or misses. Dunno....I did just replace the plugs in it though...installed bosch 4's. Spose I will repace the plugs cap and rotor also.

Thank again guys.

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

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129

Nov 16, 2004

#5

• Nov 16, 2004

• #5

numbers look great. i dont look at the absolute number so much as the relative numbers - there are enough variances in methodology to create deviation (you and i could check the same motor and get different results because we have different methods).
however, your numbers are smokin.

keep pulling codes and checkin sensors - JR has posted ECT and ACT values before in here if ya need them.

good luck.

 

jeffnoel

Founding Member

Aug 31, 2002

1,638

5

37

Clovis, CA

Nov 17, 2004

#6

• Nov 17, 2004

• #6

fost9508, how many miles on that motor?

 

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fost9508

New Member

Aug 28, 2004

131

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Nov 17, 2004

#7

• Nov 17, 2004

• #7

the car has about 120 k on it. I have heard high compression readings can be due to carbon build up??????? Is this possible?

Thanks

 

8

87stang205

New Member

May 17, 2003

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Nov 17, 2004

#8

• Nov 17, 2004

• #8

Carbon build up can definetly cause a High compression number.

 

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fost9508

New Member

Aug 28, 2004

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Nov 17, 2004

#9

• Nov 17, 2004

• #9

what is the best way to determin whether or not I have carbon build up in the cylinders????? I did remove the TB and upper intake and they had quite a bit of carbon build up on them. So I don't know what to do now.

thanks,

 

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fost9508

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Aug 28, 2004

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Nov 17, 2004

#10

• Nov 17, 2004

• #10

Asumming I have carbon desposits in the cylinder, is there a product I can buy that I can dump in the gas tank or somewhere to remove the carbon???? Also, would me compression results be as consitant as they are if I had carbon deposits????

Thanks for the help guys!!!

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

31,179

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Nov 17, 2004

#11

• Nov 17, 2004

• #11

fost9508 said:

Asumming I have carbon desposits in the cylinder, is there a product I can buy that I can dump in the gas tank or somewhere to remove the carbon???? Also, would me compression results be as consitant as they are if I had carbon deposits????

Thanks for the help guys!!!

Click to expand...

yep, deposits can artificially raise the CR. they can also lead to preignition

one of the products out there is Seafoam. i have not used it, but many have and had good results. i am leary of such products and would not use them on a motor which is operating alright (i have read a few horror stories too - but dont know if it was operator error).

the deposits would likely have very little effect on compression results (no discernable difference in your testing).

if you are not pinging or seeing some sort of issue, i personally would leave well enough alone. carbon deposits are normal on about any motor.

good luck.