Let me introduce myself first, I am Keaton and Ive been a member of mazda247 for a while, however the forum seems to not have anyone that has any knowledge of diagnosing issues. So: I got this MP3 that was running terribly, turns out low compression on all cylinders, running lowest from #1 to least lowest #4 in that order. Previous owner "rebuilt the engine" and I am assuming re-used the head bolts and gasket and did not torque correctly. So I went ahead and replaced them yesterday. After re-installation of everything, and correcting the timing, the engine now cranks beautifully (before it cranked hesitantly), however, will not start. All of the sensors, plugs, and blah blah are connected. Fuel collects in the cylinders from not firing, so injectors work. Spark tested the plugs, so that is good. There is 0 vacuum in the manifold, I have smoke tested and found a pinhole leak, but nothing else. But once during cranking, randomly, a thunk noise occured and vacuum raised exponentially for a short second. Last thing I have is compression to test (Don't have the tool), but it started just fine prior to the head-gasket replacement. scanned and all the sensors seem to be reading fine.

Important notes: Took a used FPR solenoid and ECT sensor from a different 2.0L protege, but the readings are correct. And I am running on 89 octane not 92.

This is just confusing and extremely annoying, please throw some knowledge at me. Thank you

 

No vacuum in the intake means no compression. Possibly it is out of time. Possibly the rings are washed out from excessive fuel or from cleaning the block for the new gasket. Add a teaspoon of oil to each cylinder and see if compression comes back. You really need a compression gauge. I need the exact year/model/engine size. I am leaning toward the cam timing being off,whether from the cam gears not being on the right cam or set for intake cam vs exhaust cam.

 

I had previously tested compression and found that from cylinder 1-4 were least to most. 4 being in good range and 1 being as low as 20 psi cranking. This is a 2001 mazda protege mp3 2.0l engine. When I removed the head the first time i noticed the head bolts were not torqued and were the probable cause of the linear decline in compression. The cylinders were able to hold coolant over the couple days that I resurfaced the head and block surface, so I am assuming the rings are not leaking. I had removed the camshafts and i reinstalled everything to ALLDATA specs, although they were partially misleading, but the timing is on point and im 99% sure the cams are in the correct spot otherwise the timing marks would be flipped. The most odd piece of information was that the random thunk i heard and vacuum increased exponentially, not sure what could cause that loud of a noise and result in that amount of vacuum. Thank you for your help I am very glad I didnt get another "check your fuses" message.

 

Is it spitting oil out the throttlebody? Alldata does not list a 2.0 engine for 2000 protege. European or Canadian model? Anyway. If it has 2 cam gears they might have 2 slots on each gear. One marked E for exhaust cam dowel, the other marked I for intake dowel. Kinda sounds like broken rings are a possibility.

 

No oil is leaking to the throttle body. There should be a 2.0l for 2001+ atleast, it is the American model. Yes the 2 cams have slots for I and E, which I reinstalled all by the procedure of Alldata (which may have been my mistake haha). But the only reason I don't think it is rings is because the coolant was able to sit undisturbed in the pistons for a day or two. But I am going to get a compression tester and get back with the results soon. But in reply to your first message, if there is no compression there still can be vacuum; without piston rings at all there can be a 1inhg. vacuum on the manifold, that is what confuses me. But thank you so far.

 

Compression test results are now (in order from cylinder 1-4): 0psi, 15psi, 0psi, 30psi.

I rechecked the timing, it is setup correctly, with the dowel pins at the top and I/E facing eachother. However there is a small chance that the cams were switched, in which case I have to ask, on cylinder one with timing all setup, the lobes are facing outward (opposite of overlap, such as exhaust is next); should they be switched? I dont see why this would cause such odd compression results.

 

So I am having damn near the same problem here everything is good compression air flow, and everything to that nature and all plugs are connected butttt the spark plugs are only sparking 2 times per spark plug... what could this possibly be??? Me and my step dad are stumped and we are both mechanics and we have tested everything we could think of...

 

The ignition should only spark twice per full cycle (two full revolutions); once after compression and once during exhaust stroke. It works by positive electrical flow through the plug after compression, then once exhaust stroke hits, the spark returns in the negative flow through the system. I found the issue with my engine was someone decided to put a race cam setup in the engine and didnt bother to adjust or buy new lifters for the valves, so all of the valves were just BARELY open; causing no compression. I think you may have a different issue, please give some more details.