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Low compression on fresh rebuild

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Old 05-28-19, 03:06 AM
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sim
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Low compression on fresh rebuild

Hi guys,
having starting issues. I know this could be a number of things and I’ve tried most I also keep fouling plugs.

i know I have low compression 65psi front back and across all faces
I’ve read I should expect low compression on a rebuilt motor, the motor is a full Bridgeport with one piece goopy seals and solid corner seals. And a second hand set of housings.
Now I did get the motor starting regular and quite well on the standard injectors but I’ve recently upgraded them to 4x1000cc grams and now the issue has worsened.

Ive had it running a few times and when it’s running it’s sound.
Do you think I should strip the motor or work with it for a bit longer, I’m slowly learning about the ecu and building my confidence but I’m going through plugs like mad and it’s becoming quite frustrating at times.

i cant even take it for a spin as I have no tax, insurance or mot.

Old 05-28-19, 03:48 AM
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Why don't fit the oem injectors so you can start it and let i idle for some time so you get the compression up?
Old 05-28-19, 05:03 AM
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sim
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Originally Posted by Maluch
Why don't fit the oem injectors so you can start it and let i idle for some time so you get the compression up?
I’ve had it idling for some time now and I’ve changed the map so I’d still have work to do on the map if I was to refit the old injectors.
Old 05-28-19, 12:51 PM
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32psi+

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Originally Posted by sim
I’ve had it idling for some time now and I’ve changed the map so I’d still have work to do on the map if I was to refit the old injectors.
I suggest saving a copy of your map before doing any modifications so that you don't lock yourself out in a situation like this. So save one now as some *NAMEOFMAP*_original.map kind of file and just save another copy to some other name going forward. I have probably 300+ revisions of my own tune so I can go back and check what has changed or copy previous values I have used to experiment.

It sounds like you need to have the car tuned but the motor doesn't sound very healthy either with only 65psi compression (which may or may not go up if car is ran some). You're fighting two things at once and neither is helping you. Solve one or the other and it will be a lot easier.

What ECU are you using?

Last edited by Copeland; 05-28-19 at 12:56 PM.
Old 05-28-19, 01:17 PM
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sim
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Originally Posted by Copeland
I suggest saving a copy of your map before doing any modifications so that you don't lock yourself out in a situation like this. So save one now as some *NAMEOFMAP*_original.map kind of file and just save another copy to some other name going forward. I have probably 300+ revisions of my own tune so I can go back and check what has changed or copy previous values I have used to experiment.

It sounds like you need to have the car tuned but the motor doesn't sound very healthy either with only 65psi compression (which may or may not go up if car is ran some). You're fighting two things at once and neither is helping you. Solve one or the other and it will be a lot easier.

What ECU are you using?
I’m using microtech lt10s with x4 box and four trailing coils.
this is why I’m in two mind if I should pull the motor anyway. When I had it running and starting on the 550s I was happy and had no reason to question the engine at that time.
I did save a map but for some reason when I reloaded it it was not the map I saved so I ended up loosing both.
Old 05-28-19, 01:20 PM
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sim
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The default map I start with is the one silverrotor posted as a stock Tll base map plus -51 in the mixtrm.
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