I changed my fuel filter this morning, was a pain in the ***. After priming the fuel system I took it for a test drive. Everything was normal so I get on it a little, only boosted about 8 PSI then I hear the dreadfull detonation sounds pop pop pop. Now my car won't idle, I can get it to start if I let it crank enough times but it dies a couple senconds after I let off the peddle. I can drive the car and it seems to run okay at higher rpms.

So did the motor blow or could it be something else?

I haven't done a compression check yet, I don't have the equipment.

Let me know.

Greg

 

Blown motor = change in compression that you can easily hear out the exhaust. It will go from sounding smooth like a weedeater to sounding harsh like a lawn mower. (Best way I can explain it)

If your motor is sounding okay at "higher rpms" as you said above, then I'd put my money on something being wrong with your MAP sensor. It is located on the driver's side, near the firewall. Check the electrical connection to make sure it's still connected, and check the vacuum line that comes out of the bottom of the MAP and runs to the back of the intake manifold.

Good luck, and if you don't have access to a compression tester, you could always test compression by cranking the engine with the lower spark plugs taken out one at a time.

 

You don't need a compression checker to check for a blown motor.

If you have a 10mm socket. Take your elbow piping off your throttle body.
Take your top plug out of each rotor housing. Take out your fuel pump
fuse (under the plastic plenum that feeds your air box if stock). And Also take
out you EGI fuse so you’re not creating spark. Turn the motor over. If you
have a consistent air being pushed out of both rotor housings. You still
have all your seals. You'll hear a gap in the air noise if one is missing.
You need a 13/16 plug socket to get the plugs out.
Good luck.

If you don't have any tools. Then just go buy a 3/8 ratchet, 3/8 3" extension, 3/8 10mm socket,
3/8 13/16 plug socket. Just get cheap ones. Doesn't have to be name brand

 

Mix up a fuel line? Pinched a line? Installed the filter backwards? On some filters direction matters, others it does not.

 

Good one, I kind of forgot he had just done maintenance to his car.

 

IF you pull the EGI it kills spark and fuel , so no need to remove both. The fuel pump still comes on but the injectors wont fire.

To the OP, do you have a boost gauge? Check your vacuum and get back to us with the amount of vacuum it is pulling at idle and what rpm it is idleing at. I recently had a customer daily drive his blown motor fd around for about 3 weeks. Hopefully it isnt blown and it is in some way related to the work you recently performed. Best way to check is the compression test though.

 

Thanks for the replies. I will check the compression this week, I need to go but a 13/16 plug socket.

I have a boost gauge and it appears to have the same vaccum as before, which is around 30, it idles at around 500 rpm.

 

Something is off. The idle is too low even if the car is stock. The vacuum also seems too high. I would raise the idle to at least 750 if the motor is stock. Closer to 1000 if it is ported.

 

Yes but my injectors leak by pretty bad. So I always pull both. I'll be fixing that
in the next couple weeks

 

However, this just lets you know if you are getting any compression. The engine can still be blown but creating compression from all three faces of a rotor (i.e. getting something like a 95/20/20). Using a compression tester is still the best thing, even if it's a $20 tester from Sears.

 

He is right. In the end you'll need some numbers to know where your at.
What I said is just to see quickly if all your seals are there or not.

 

I'll check the compression this weekend and let you guys know what I get. BTW car is not stock.

 

That idle level and vacuum don't make much sense.

 

Idle was much higher before this happend and the vacuum is .30 bar I believe. I am using the knigh sports ebs iii boost gauge/controller.

 

vacuum line?

 

I hope!

 

Was your "pop pop pop" like unburnt fuel shooting fireballs out the exhaust when you hit a rev limiter? Or was it more like shaking a can of rocks? If it was good solid pop like fireballs you are probably ok.

 

Sounded like the rocks unfortunately.

 

check your map sensor vacuum line, could have popped off also.

 

Map sensor vacuum line is still attached. I just got a compression tester and will test later this evening.

 

I ran the test and it looks like 2 bad seals to me.

http://www.youtube.com/watch?v=cHKQ5Bi3LS0

 

That looked like 2 low, 1 high, which is the sign of 1 bad apex seal (between the 2 low chambers).

Dave

 

Sorry to hear

Did you do something wrong when you installed the fuel filter? Weird way to pop a motor.

 

yeah, that kinda what I had to do many years ago. I blew a motor and still daily drove it for 3 or 4 months. I adjusted the idle, so that it idled at around 1k with a bad apex, just so I can daily drive it and got around 6 miles to the gallon (gas was much cheaper back then) I drove it until it was probably cheaper to just replace the motor than it is for gas. I was afraid to drive into and out of gas station because every once in a while it would shoot flames out at light throttle. I drove it so long that when I finally did replace the engine, I forget I had adjusted the idle to compensate for a bad apex. I was stumped for a week, I can't figure out why the new engine was idling at about 3500 rpm. I guess that kinda explained my gas mileage. The car ran crappy at low rpm (rich as hell) but at higher rpm and better sealing due to centripital forces, the car still ran strong.

 

I'm pretty sure I didn't do anything wrong when I installed it, pretty straight forward.

Now I am contemplating whether I want to do the rebuild myself to save a couple thousand or have someone with experience.