Another modded 951 not starting
 

I just finished my 951 after 2 years of work and it cranks but won't fire up.

- Darton MID sleeved 2.7L block
- LR Garrett Super 75
- LR Cam
- LR MAF/MAFterburner
- LR 951 MAX chips
- LR Stage 1 head w/high velocity exhaust
- Cometic head gasket
- LR Stage 3 intercooler
- LR Boost pipes
- LR dual port WG
- Adjustable FPR
- 55lbs siemens injectors
- 3" race exhaust
- Innovate WB O2
- Raceware head studs/rod bolts
- MSD Blaster coil w/magnacore wires

The engine was completely disassembled and rebuilt with all new gaskets, bearing, rollers, belts etc. Everything seems to be in sync but it won't start. It fires on occasion but nothing consistant. The MAF/O2 stuff checked out properly. I reinstalled my factory injectors last night and it felt like it was about to start but then it would die. I found out my number 2 injector was leaking really bad and I could only hold about 20lbs of fuel pressure. I believe the lack of fuel pressure was to blame for it not starting, but does that mean my 55lb injectors are not working properly? Of course there could be more to it than meets the eye which is why i wanted to get some other minds on this and hopefully figure it out. Thanks

Are you getting spark?
Are the injectors firing?

You are running a "chipped" DME/KLR? Were the chips burned for your setup?

If it is only holding 20 psi You may have flooded that cylinder,,,I can't stress this enough ....BE CAREFULL.....you can hydrolock a cylinder with fuel if your injector is leaking. his can result in a bent rod or broken piston :(

To be safe I would unhook the coil and remove the plugs and turn it over to releive the cylinder of excess fuel.

With the info you have provided I would look closely at the fuel system mostly the injectors. Make sure all is good with them before going any further or you could have some serious problems.

Once the fuel system is sorted then I would check the spark by removing a plug wire and inserting a new plug to see if your ignition is fireing.


Try to narrow it down a bit starting with fuel,then ignition

As far as I know, the plugs are firing...they are brand new and there is spark between the cap and each individual ignition wire. The #2 injector was leaking out of the head, not into the cylinder (probably just not seated correctly) so I'm not too concerned with flooding the cylinder. Would the lack of resistors for the 55lb injectors stop it from starting? I was told they were bolt on, but I've learned not to believe everything when it comes to that sort of thing. It was my understnading that the injectors would still work without the resistors, but it would work the computer more. The chips I have were burned for my car.

there is an earlier post where someone used 55lb injectors on their car and now it won't start.

There's another thread but his engine is starting, it was having problems revving up. It looks like the MAFterburner was the answer for him, I already have it wired in and ready to tune as soon as it starts.

So what is the fuel setup like now.

Is it holding psi?

Does it start and die or no start?

It should be able to fire up and idle on the dme idle map if the TPS is adjusted properly, check to make sure the TPS is functioning. This would eliminate the MAF setup altogether.

What is the resistance on the injector? 2.4 2.6 16.0 5. ?

Test across pins.

ok to be diffrent for everyone else right now. did you load a tune into your Mafterburrner? if not it may not start. I would download one of the ones on the LR site and load it. if you havent allready. and go through and set it all up right. that can cause a headache. also another thing to check is your dme relay, fuel filter, GAS, and maybe some other stuff i cant think of now.

it will not start if the wireing for the maf is not right or the maf is not hooked up. and if i remember mine wouldnt hold an idle with out a tune. i just downloaded the one from LR.

Well i talked to the guys at Lindsey and they said it should start fine as long as I have thier chips in. I wasn't able to work on it last night so I'm still suspect of the fuel injectors (which I also need to check the resistance on) so I'll be starting there and work my way to the tune if that seems to be the issue.

Hmm, I have always been able to start and idle with the AFM unplugged, does the MAF setup override the idle map?

After thinking...... the new chipset should have the idle map built in for the bigger injectors..correct

yes, the chips are set up for my injectors and cam etc

Okay, so I reseated the leaking injector and it started right up. There is a fairly steady idle (not sure what's it's supposed to be like with the new cam) but lots of noise. There is too much to describe, sounds like detonation not much like mechanical banging.

Good to see it started

Did you pump the lifters?

Is it that type of Sound at all.

How is the oil pressure?

I had a case where the bolt wasn't tight enough on the crank snout resulting in some strange noises from low oil pressure.

The oil pressure gauge was steady just above 5...but I didn't want to keep the engine running to see if it dropped once everything warmed up. I double checked my crank bolt, it's good at 155ftlbs. Initially, it was idling but it was rough and didn't sound right. I did a compression check (all cylinders were between 170 and 175) after the check I tried starting it again and it still starts right up but it revs up (sounds a lot more normal) and dies. I do have a vacuum leak on my boost pipe but I don't think that's the only thing causing it to die off


***If I remember correctly, my compression when the engine was stock was around 155...is there anything in particular I need to worry about with the higher compression?

um.... detonation? melted pistons? probably only under boost, however.

well is 20-25lbs a relatively big difference? I'm guessing I'll just be running less boost. If it is an issue, can't a thicker HG lower it back down to the 155 range?

increased compression ratios increased volatility, thus increased likelihood of damage. if you are running less boost, this danger is diminished. you can get thicker head gaskets, but i am not sure how much they would decrease the compression ratio.

Okay, I did another compression check. The first time I did one cylinder at a time (leaving the spark plugs in the other 3 cylinders...with the coil/fuel pump disconnected) This time I pulled all the plugs out first, then checked each cylinder. So the results were a little different: 165 on all cylinders. I don't think the 10psi increase will matter a whole heck of a lot and if it does I'm almost positive a thicker HG will be able to correct it.

Not to be negative but the compression test was more accurate the first time you did it with the other cylinders plugged. I think you'll be fine, like you've said before, easy on the boost (you shouldn't need much with you're set up) and don't drive (always) like you're running from the cops.

UPDATE: I went through all of my vacuum connections and made sure everything was properly connected. It still refuses to hold a steady idle and dies off 2-3 seconds after firing up (and it fires up immediately once the key is turned) For the 2-3 seconds the engine is running it sounds like a million bucks. It was not starting at all with the 55lb injectors, so my stock ones are still installed. Could the fact that my chips are set up for 55lb injectors be the reason why it won't run? My TPS seems to be dialed in correctly as well.

About my 55lb injectors, what do I need to do in order to get them installed properly? Someone mentioned testing them across the two pins...with what? Please excuse my lack of understanding, I've never really dealt with the electronic side of the car and I have no previous experience with electronics. So if anyone knows exactly what I need to test, how to do it and what to use, I would really appreciate the help. Thanks

Check the OHM resistance across the 2 pins on your 55# injectors. Any decent multi meter will have this function.

You will want to make sure they are not the high impedance injectors 16 ohm draw. They should be either 2.4 or 2.6 or 2.8. If they are not you need to get the low impedance injectors and as some have said you will need the ballast resistors, however I have been able to run 2.8 injectors on a 5 ohm system w/o them.

Yes it will absolutely die if your chips are set for 55# injectors, it is running totally lean. You could try to run the fuel pressure up to around 60 psi to see if it will sort out temporarily but don't boost it.

You will need to either re install stock chips or get your injectors figured out.

I personally would check the injectors first and if they are the high impedanc eI think you will have found your problem. If they are the low imp then try the balast resistors.

If all of that doesn't work try stock chips and injectors to make sure you can get any other bugs sorted.

Thanks for the gouge, I'll check that stuff out ASAP.

Assuming you got your injectors from LR just like everything else you have they are 2.2 ohms, low impediance.

I actually bought them from someone on rennlist, so I need to double check them. He said he ran them without any electrical modifications but I'm going to start looking into it anyway

are you able to monitor your a/f ? what does it show?

I checked my injectors and they registered at 12.8. My A/F gauge shows that I'm incredibly lean (for the few seconds the engine is running). So what do I need to do in order to get my injectors online? I'm guessing I'll have to install resistors but once again, I'm not too savvy on the electronic issues.

where did you get these injectors? why not get the correct injectors?

I got them from someone on Rennlist, he claimed he had been using them in his track car. At this point, if there is a workaround for the injectors I have, I need to utilize it. I was able to dump the $$ when I was single but now that I'm married things aren't so simple.

i'm running the correct 55lb siemens injectors purchased from marren for around $60/per. i find it amusing that lindsey sells the exact same injectors for double the price, and more surprising that people actually pay that much for them;
http://www.injector.com/

lindsey's ripoff price;
http://tinyurl.com/2g8jqf

here are some related threads for info on the resistors;
http://forums.rennlist.com/rennforums/showthread.php?t=182462

http://forums.rennlist.com/rennforums/showthread.php?t=55851

http://forums.rennlist.com/rennforums/showthread.php?t=52132

personally, i would rather spend the $240 knowing you'll have the right injectors, rather than using resistors to create a hack job.

Wow, I had only seen the $400+ that LR charges...I might be able to swing $240, especially if I can sell my current ones. Thanks for the links, I'll have to see what I can work out.

The chart on that site says I would need 88+lb injectors just to make 400hp...with my mods is there really a need for more than 55?

Did you ever check the Ohm resistance?

OOps read too low

Yep that is your problem

IMO you can't go with those(current) injectors as they are of a higher restance unless you want to change over to a standalone that can use either driver rating.

Have to pony up unfortunately

i don't understand why anyone would want to use the high-impedence siemens injectors for the 951 when the correct low-impedence injectors are available for the same price. what's up with that ?

I wouln't even think of it myself, it really doesn't make sense. Not to mention that the peak hold are a more accurate style of injector anyway.

Unfortunately, with the strange 5 ohm setup of the DME there can easily be confusion as to which direction is OK to go with resistors.

FYI use low imp injectors with resistors not high (saturated) impedance.

I also think it comes down to price.

they are the exact same price. $59. they are also the exact same 55lb flow. one requires resistors, the other is plug-and-play. why anyone would want to pick the more difficult (and expensive since you also have to purchase resistors) solution is what i don't understand.

don't pay attention to the chart. :) 55lb is fine for around 350whp.

also, it just occurred to me that whoever you bought the injectors from were probably selling them for the exact same reason you are now. :) i'm betting those injectors are the hot-potato of the 951 world that keep getting passed around and never used.

Ii was meaning used. I guess I should be clear.

If you look for used injectors you can find high imp injectors cheap everywhere. Low imp are abit harder too fiind and generally at a higher price.

Anyway I'm glad he was able to get it figured out before hurting anything dramatically :)