take both spark plugs out for compression test car cranks slow??
 

Ok I just want to make sure that doing a re rebuild on my engine is the correct thing to do. So of course I'm doing compression tests etc... and so far these are the 2 reasons I'm going to tear my engine down and rebuild it again after driving only 2.5k miles on this rebuild.

1. compression shows only 90psi front rotor and 100psi rear rotor when about 500 miles ago it showed 97psi front and 105 rear.

2. I get 1 1/2 quarts of blow by only 2 days after an oil change.

On my last rebuild I used brand new everything except sides seals (however they where spec'd out as per fsm), rotors, and housings (including side housings).

My question is when i do a compression test it seems like everyone says to take both spark plugs out of the leading holes however when I do this the car cranks incredibly slow ( http://media.putfile.com/cranking-speed ). Now if I keep one of the spark plugs in and do the compression on the other rotor it cranks fast. whats the deal with this? Anyways any help would be great cause seriously I don't want to rebuild my engine again but if I have to then I will.

bump? kevin landers where are yah bud :)

that is rather slow but your battery does look slightly discharged(battery voltage should be right around 12.6volts static), try hooking a battery charger up to it and charge the battery while doing the test. small variances can cause different results for compression, those numbers don't look incredibly bad but if it was during cranking at that speed they would be a little low.

charge the battery or jumper it to another to aid in cranking speed and be sure you hold the throttle wide open for more airflow during the test.

for blowby, what are you using for crankcase ventilation? at higher boost levels crankcase blowby will increase drastically so i suggest installing a oil catch can to see how much oil you are actually losing due to blowby out of the motor not past the seals. if it was internal blowby you would see huge plumes of smoke on hard accel. IMO i dont think you have any problems but just need to do some setup changes to the car.

my car with a catch can spits about 1 quart out in just one day of relatively spirited driving, which is fairly normal depending on how you have it set up.

btw, where's those pics of the radiator? :p:

I think he's not losing oil, rather, he's adding 2 quarts of gas over the span of 2 days.

sorry for taking over and the noob question but could someone explain blowby to me. I know in piston engines, its the loss of compression through the vavles, but don't know what it means for a rotary.

thanks guys for the replys. Karak I haven't forgoten about you, i had a neigbor come by that happens to have a buddy that welds aluminum so I think he is going to fix it and then i will sell it to you. If he is able to fix it I'm still not going to charge much for it maybe somewhere in the 125 150 shipped range and those pictures will come asap. As far as the car goes yeah i'm getting gas in my oil, and a shit ton of it at that. basically 2 days ago I changed my oil and today I am a quart and a half over the fill mark on the tip stick and this has been happening to me since the rebuild. I thought it was cause i was running dumb rich however after getting it tuned I'm getting it just the same if not more!

The 90/100psi compression results was from me putting the tester in one of the leading holes while plugging the other with a spark plug (wich makes my cranking normal speeds) and with the throttle wide open. I know it's really not the battery as the slow cranking with both spark plugs out happens every time and AS SOON as I either plug up all the holes and crank or plug up one hole with compression tester and one with spark plug it cranks fast. Strange shit i'm telling you...

zigity bump!

heylow?

Think ya be needin a new title... this one's kinda not very catchy... maybe 'check out this hot asian chick' will get Ted's attention?

does the car tend to flood out sometimes? blowby of fuel into the oil really only happens due to flooding during cranking. once the engine is running there is no fuel after combustion to get into the motor, at least not as much as you are talking about unless you are having an injector sticking.

through the RINGS

hahah no shit man, my last few threads have been very unpopular not exactly sure why? I was thinking that only newbies get on this site now and unless we are talking about rims, body kits, cai's or, exhuast setups then they don't know what I'm talking about :dunno:


Karak you are the second person to say it could be a stuck injector however I've got people like aaron cake say that it couldn't be from the fuel fuel system like that? I think just because two people have said it I'm going to get my injectors tested today. Oh and about the flooding, there are two things this car has never done from the rebuild, the first thing being smoking. The car never smoked, even after I started it up for the first time or anything just a very clean burning car. 2nd thing being flooding. I can turn the car on for one second and turn it right back off and turn it on again without any flooding. The only time I had a hard time starting it was right after the rebuild and then the closest it came to flooding was the other day when i went out for a VERY "spirited" drive and i turned it off and then 20 minutes later I turned it on. It took me like an extra 5 seconds to start it.

ok just got back from the local machine shop to have my injectors tested and basically they do everything in ML instead of CC so I was kinda confused but basically they tested the 890cc injectors first and at 40psi and wide open they would have to turn off the machine because it would fill the 130ml tube up before one cyle was over with and this happened as well with the 850cc injectors. So then he turned it down to 20psi and ran the test and this time the 890cc injectors flowed 75ml and the 550cc injectors flowed 65ml so what is this saying? I do know that none of them where leaky or anything like that and they all flowed exactly the same as far as the numbers stated above however when we took out the filters one of them was very clogged with what looked like teflon tape??? Anyways can anyone explain to me what those test results mean? and if they are ok? Thanks.

Dude, 1cc=1ml. Now about the pressure/cycle thing I cant tell you w/ out knowing what the injectors are rated at that pressure(psi) and length of cycle(sec. or min.)
Dunno if, for example it's 550cc/min at say a particular pressure. Hope someone can help. Would like to know myself. Wonder if the parts guys at the dealer would even know.

Good luck though, Been watching your progress. Hope it works out.

thanks for the reply man I was just hoping one of them was leaking or something so that it would have been my problem but they both flow perfect and they both flowed alot! Like I said at 40psi those things filled up the 130ml tube after about 10 seconds. I think the cylce is a 10-15 second cycle.


edit: when I was getting the car tuned I kept asking steve is the fuel pressure ok is the fuel pressure ok and he was like yeah it's not leaning out so it is fine however he never really looked to see what pressure it was at and I have that thing set at like 47psi durring vacuum. Is that ok?

Base pressure (no vac) should be around 40-43.

thats what I'm screemin' so me being at 47 at idle with vac what is that doing? will the microtech compinsate for it or is it just to much fuel pressure? I have been running basically this same pressure since the rebuild. However I can tell you one thing I just got it all back together and if one positive thing came out of this i can tell you that man my idle has never been so smooth since I put on this extra ground from the battery to the body. Geez! It's like a stock car all over again :)

Your car needs all the extra it can get. ;)

47 under vac would scream stressing your poor pump needlessly to me, it can be compensated by lowering the duty cycles.

damn if I lower the pressure it's going to lean out the tune so that kinda sux dick! I don't know what to do. The starter is still stupid, it will be slow some times and fast other times, i'm going to have to say it's got something to do with the ignition switch maybe getting tired or something. When the engine is hot though and the starter doesn't crank has fast it's harder to get my car started but I don't think thats hot start as much as thats just not getting enough compression to turn the bastard over.

yea, unfortunately Steven should have said something. now you will have to live with what you have or have it retuned. still not sure that that would cause an extreme rich condition though which would force fuel into the oil, the only other reason i could think of would be extremely worn iron plates or side seal clearances being at the wide end of the spec border along with a rich condition.

I don't know, we've bypassed the damn switch entirely and still had some strange issues...

well after I added the ground I cranked that bastard via a line from the positive on the starter to the battery several times and no problems at all. I'm talking probably a good 20 times or so and it was fast everytime. then i go and get it and it's fast then stop at the gas station, fill up and go to start it and it's slow :(


Karak: thanks for the reply the only problem I'm having is that a) we actually spec'd them out closer than what i said, sonicrat is the one that did the specing out and he said we spec'd them at 25 thousandths also before this rebuild I got no blow by at all so the side housings being overly worn out is just hard to understand :dunno:

hmm, i would have to check the conversion since i spec in metric, when specing new seals i do them right at the tightest tolerance since they will wear some almost immediately.

for the starter, it just sounds like a faulty starter, a brush sticking would cause intermittent slow cranking and the added resistance could push the stator enough to contact both brushes. that is my best guess anyways. whack the shit outta that sucker a few times with a mallet and see if it cranks normally.

could be why the starter was a tad bit on the cheaper side for an rx7 starter. Oh well. I'll wack it and see what happens, lol. sorry sounds funny. Anyways I may just break the engine down and do the freakin rebuild and buy some new housings and get these side housings relapped. I kinda want to put oem seals in anyways.

What seals did you use? RA?

Did you replace the oil-control rings and install new inserts?

Are you ported?

How many miles on your internal parts?

Where exactly is your crankcase ventilated (just to make sure)?

The fact that you don't smoke and can start every time are very good... I would consider doing more tests etc. before even *considering* a rebuild.

Also, IIRC you want to comp. test out of the Trailing plug holes to get the 'sharpest' reading. I.E. Remove the EGI fuse, remove the top two plugs and just take turns screwing the tester into each hole. Use a truck (or some other "powerful type" vehicle) to "jump" your car for the duration of the test, to get the strongest cranking speed. Try mixing it up and using the 'hold' function on whatever tester you're using to see what the MAX compression is.

I dunno man... I feel your FC related pain. Just remember that this car is truly amazing when working properly. And even though that Type-S you sold me exploded, I want to see you fully enjoy your TII... LOL. :bigthumb:

the type s exploded???? are you serious? how long did you have it before it exploded? How the fuck did it explode? man that sux! That thing was on my car when I got it but the owner told me he didn't have it for long. Man i'm sorry to hear about that. Anyways yeah i used RA seals :( if I could go back I would use oem and will if i open it back up. I did replace oil control rings however the inserts where fine so I didn't have to replace them. I do have a street port using the racing beat intake ports and also their race port for the exhaust. I just have everything vented to the atmosphere right now however do you really thing I could get this much blow by from not the proper crank case ventilation? kinda seems a bit exsessive to me. As far as the compression test goes kevin landers says to do it from the leading holes so thats where I did it from??? I didn't use anyone to jump me so I may do that just to see if it boosts me up a tad. Also thats what I did to see the max compression except on mine if I just put the comp testers on and crank it automatically builds up until I press a little button to let the air release. Sorry if this post sounds dumb I just woke up :)

Ok guys I'm really at a loss. Do any of you guys think this kind of blow by can come from anything other than internal issues. Reason I'm asking is because I have to make a descision soon about wether or not to rebuild. I've got some brand new 3mm apex seals that I can buy for around 275 and then the side seals, oem oil seals, and apex seal springs would cost another 200 bux so already I'm at almost 500 bux in a new rebuild however I'm guessing I can sell my nearly new oem apex seal springs and ra seals for about 200 bux and make up some of that cash. I don't know guys i just want to know rebuilding the engine is the only thing left to do. I guess I could sell my nearly new ra viton oil seals as well. Anyways if yall can help a brother out that would be great! Thanks.

It doesn't make a whole lot of sense to me.... i know the side seals were in spec so long as they went back in the locations they were in when we first put it together, the oil control rings were good too. Why it's filling up with gas so quickly is rather annoying unless your injectors are simply dumping all of the fuel into the engine when you turn the car off...

its gotta be the sideseals dude.

i'd open the motor up and shave some NEW sideseals down into spec and reassemble... with like .001 clearance on every single one.

yeah fuck it, your right it's gotta be the side seals. Well while I'm at it I'm dumping some 3mm oem seals in there as well as relapping the sidehousings and powerdercoating the lim, uim, intercooler piping, front cover (is the front cover something good to powerder coat or is that bad?), and waterpump housing. I also need to get a new front side housing and port match with the one I have. Hey sonic I know the side seals went back in the same way we spec'd em so thats not a problem but who knows the RA seals could have fucked up or something, dont' know till I open it up. hey do you know if there is a setting in the mt that will make the injectors dump? Also I don't think it's that cause if it was dumping fuel I'd get a shit ton of smoke when starting up and I get none. Also is there any way it could be oil seals? If so I want to replace them. Basically I want to replace anything it could be internally with oem parts.

if one of the injectors is grounding out because of wiring touching something, it will shoot fuel.

yea this will only happen if there's a break in one of the wires and it's grounded. even then with the ignition on you should be able to hear fuel rushing out of the injector. if you take off the UIM and do this and the one of the wires is grounded you'll see an intake runner fill up with a puddle of fuel.

Ok I'll try this out then, thanks guys. I do hear a noise up there right when I turn the key on but then it goes away. I always thought it was the microtech turning on the fuel pump to get pressure???

you can also install a fuel pump cut off switch, use it to kill the engine when you park it. try that for a week and see if the issue goes away, if it does then there is a problem with either the microtech setup or an injector that isn't shutting off as it should.

hum...............very good idea karack, props man! :) thanks I'm going to set that up tonight!!!! I'll let yall know how it goes.

edit: the only other thing it could be if it's not that and it's not side seals is that when we where doing 4th gear rolls we where feeling break up in the higher rpm range and he said it was fuel not getting burned. He said to try differant cables to see if it was that cause I had the eccel racing wires so I went to msd and it's still here so maybe something is happening to my fire up top and causing the fuel not to burn like he was saying thus creaking blow by?

something else I just thought of is that I used to be able to go further with my 550 primaries before I would get this tons of blow by however now with the 850's I'm getting more blow by. I guess this would just have to do with them being bigger injectors but this may be where the blow by is comming from, the primary injectors.


well I just checked the injectors for voltage durring the test mode on the microtech and I found that all of them get about 1.15 volts. Is this correct?

Just wondering though if your injectors were atomizing the fuel when it cycled or was it just pouring out of the jet in a stream when they tested. Be kinda hard to ignite fuel in lquid form than if vaporized don't you think? Just curious if that's why they lowered pressure during testing. Would still burn I would assume but maybe not enough which might explain the fuel in oil. Just my .02.
Really curious as to why you'd have this condition.

I know it was just pouring out of the testers so it was probably just on at like 100% duty cycle or whatever the max is without messing up the injectors. It's a little back woods machine shop that does this so I know he's not to hip on whats going on with them but as far as flow is conserned they where spot on with eachother.

i'm also getting some puerto ricans that race rx7's for a living telling me that it could be the fuel pressure regulator being that the one I got was an ebay special. I dont' mind buying an areomotive a1000 but I just want to make sure that this could indeed cause a problem like this. Does everyone with aftermarket fuel pressure regulators when the car is turned to acc position the fuel pressure will go up to normal and then bleed down to about 20 or so psi? Anyways if it could be a possibility that it is my fpr I will change it but if it has nothing to do with it then I won't. thanks guys for the help so far! Please stick in there :)

lol, new problem, jeez! I just called summit racing and told them I wanted to order the a1000 bypass regulator but told them I have rubber fuel injection hose and not AN fittings and that I would need some fittings for that regulator from them as well and he said simply they aren't available because barbed fittings are for low pressure stuff and the fpr was made for high pressure. I told him I had an ebay special regulator that had the an fittings on it and there was no leaking and that I was running 47psi of pressure with no problems however he said there is no way to get barbed fittings for it soooooooooooo I'm at a loss for how I can get away with doing AN fitting fuel lines yet still get a better fuel pressure regulator than what I've got.

barbed fittings work fine for high pressure fuel systems they just need to be snugly tightened down.

well he said they didn't have that cause they wheren't made. Looks like I'll be trying to find some sort of adapters then for that fpr. they have a 3/8ths barbed fitting that will work I could probably squeeze our 5/16 hose on that.

did you get a chance to tear down that motor?

nope i'm trying to do everything first before I tear it down. If all else fails I'll tear it down. Jeez i really don't want to though