Penglii's 1989 TGP

[Penglii]

you could just ohm test the injectors.

 

n/a cars are a different size so it would run f-ed up even if they were good.

Yeah, that occurred to me today... I thought it would be a cost effective way to potentially get my car back on the road (Low on funds these days), but you are right I might as well just OHM check the TGP's injectors and go from there.

 

if it smells like fuel i'd look at ignition

Yeah, I'm gonna be checking for spark at the front three plugs before I pull the plenum.

 

I had only like 5 minutes free today to examine the car, during which I fired her up for a very short while and did a walk around. Bent down by the tailpipe and I can hear the putter of the misfiring and I can smell the raw gas that is being forced out the exhaust... in fact there is the telltale gray puffs of atomized raw gas out the pipes. Not coolant smoke, obviously not running lean, not black so the fuel is raw not just rich burning.

 

I suppose this tells me that one or more of the cylinders is either not getting spark, or is getting getting too much fuel dumped into it so the spark is going out. Either way I'm assuming that fuel is being injected into the cylinder(s), is not being burnt at all, and is just being pushed out during the exhaust stroke.

 

My first instinct is to think that since I'm never seeing any black smoke it cannot be leaky injectors... but I guess I should OHM check them anyway and not just assume anything.

 

I'm sort of hoping it is somehow the injectors... because I cannot find a way to get anything to reach that lower ICM bolt. I can even jamb a 13mm nut driver in where it ought to be and there is something mysterious and stationary sitting right in front of the left hand side of the bolt making it so I cannot reach it.

[mfewtrail]

My first instinct is to think that since I'm never seeing any black smoke it cannot be leaky injectors... but I guess I should OHM check them anyway and not just assume anything.

 

With leaking injectors, you're not really going to see black smoke. At idle on a car w/ leaky injectors, it's going to be a color almost between a white & blue in color. The smell will be a dead give away that it's raw gas out the tail pipes as it will nearly choke you out. If the injectors were leaking, you will usually notice a gradual change in the way the car starts. After it's sat a while and the fuel pressure had bled down/leaked fuel into the cylinders, it would take some extended cranking to start it and then you would be greeted with small clouds of raw gasoline smoke out the exhaust. If you suspect leaking injectors, rent or borrow a fuel pressure tester and you can rule them out in a few minutes by doing the following:

 

1. Install the fuel pressure gauge on the fuel rail schrader valve.

2. Turn the key on to let the fuel pump prime.

3. Note the pressure reading on the gauge and see how quickly pressure drops off. It should not drop more than 5psi in ten minutes time. If it drops quicker than that, you have a leak.

[Penglii]

Well that certainly sounds like what I'm experiencing!

I will be checking for spark and for fuel pressure leakdown this evening.

Depending on what I find out I will probably also be pulling the plenum and OHMing out my injectors.

 

Thanks for everybody's help so far

[Penglii]

Well... finally checked for spark, and all 3 coil packs are firing nice and strong... so that finally rules out the ignition system I think.

 

Picked up a new plenum gasket set and 12 new injector o-rings. Totally forgot to get a fuel pressure tester... but I'm feeling very confident there's some leakdown going on here so I'm just going to go ahead and replace the injectors.

 

Being on a majorly tight budget here, I'm going with some 26# injectors from a Multec-1 3800 that I ordered last night from ZZP (shipping from michican to wisconsin so they should be here quickly). Maybe not the worlds most exciting choice, but the price can't be beat and I understand they will work just fine... and hey, it's still an upgrade from the probably 21 year old stockers. Eventually I want some accels, but that's not quite in the cards right now.

 

I wanted to get the plenum pulled off tonight, but I did not get home from work fast enough and so the sun went down too quickly. Oh well, slow progress is still progress.

[mfewtrail]

Since you're pulling the plenum, do the following after you have it off: Unbolt the fuel line hold down(right beside the oil pump drive), and remove the rail + injectors intact w/ the fuel lines still hooked up. After you get the rail up, place some paper towels up under the injectors. Turn the key to the on position to prime the fuel pump. Now let the car sit a while and watch and see if any fuel is dripping from the injectors. The paper towels will help you clearly see if any of them are leaking as they'll be wet. It's a good idea to take a shop vac and vacuum up all the crap around the injectors before pulling the rail out. That way you minimize the amount of dirt/debris that drop into the engine.

 

EDIT: If you haven't already, check the fuel pressure regulator while you're at it. If you have a hand operated vacuum pump, pull a vacuum on the fpr and then pull the vacuum line off. If fuel is present in it, it's leaking. Without a vacuum pump, you can suck on the vacuum line with your mouth(LOL)....but you're going to get gasoline in your mouth if it is leaking.

Edited October 12, 2010 by mfewtrail

[Penglii]

Sounds like a plan... which one of the TB vac lines goes to the FPR again?

Edit: N/M I found my diagram.

Edited October 12, 2010 by Penglii

[Penglii]

PROGRESS REPORT:

 

Checked the FPR vac line last night... no mouthful of fuel, so I think I can rule that out.

 

ZZP got my injectors in the mail this afternoon, so I ought to get them in the next few days... AARGH waiting for them to get here is already killing me... I want my car back on the road!!

 

Pulled the plenum off, and OHM'ed the injectors... they all check out at around 12 OHMs, so it's not a resistance issue.

 

I ran out of time to pull the rail tonight, it got too dark, so I'll do a leakdown test tomorrow but I think I know what the results are gonna be.

 

I did notice that the injector body, that can be seen with the rail still fully installed, is cracked on at least 2 of the injectors. Granted it's the plastic outer housing of the body of the injectors that's cracked... but I bet it's a clue as to what I'm going to see tomorrow when I pull the rail and get a good look at the injectors themselves.

Edited October 13, 2010 by Penglii

[Penglii]

OK... So I might have made a dumb move with the fuel injectors I ordered... I guess I'll find out.

 

So... being that I could not afford the $300, give or take, for the 26# accels I want... I went with the most cost effective choice I could manage within my timeframe, which was a set of GM#12554271 injectors from ZZP. From my research that part number would flow 26# at our fuel pressure. (Robert set up my main tune for 26 pounders) Seemed like a good way to go until I can raise the funds for the accels.

 

Anyway, it appears they screwed up my order a little bit and send me GM#12561462 injectors... which they list as being 28# at our fuel pressure. However the internet cannot give me a straight answer... from the hunting around I've done they might flow anywhere from 24# to 28#

 

This does not calm my nerves any... but I guess at this point I don't have much choice but to try to run them and see what happens. I'll find out on Sunday, which is my scheduled day for buttoning everything back up. Wish me luck I guess?

 

EDIT: Perhaps I'm in the clear... I guess the #12561462 injectors they sent me were used in z06 vettes and were 28.8# at their 58PSI fuel pressure... meaning they are ~26# at our fuel pressure and I should not worry so much. LOL

Why is finding good information on the internet so much like pulling teeth?

Edited October 15, 2010 by Penglii

[RobertISaar]

i know all about trying to figure out factory injector flowrates...

 

took me forever to constantly cross-reference enough injectors to figure out that the 95-99 3100 injectors flow from 17.4-18.2 lb/hr at 43.5PSI... the previously thought values were 19.... messes with quite a bit of stuff if you don't nail them perfectly.

[Penglii]

It's a blast I tells ya.

I suppose I'll have to keep an extra close eye on my BLM and Injector Duty Cycle for a while to be sure that things are gravy.

[RobertISaar]

that's a VERY good idea...

[Penglii]

How is the backup/saftey tune set up in regards to the fuel injectors? Is it advisable for me to continue to run that tune still for a while while I ensure that everything is A-OK with the new injectors, or should I switch right over to the primary tune? I don't remember if you explicitely mentioned how the backup tune is set up in regards to injectors, other than the lowered boost limit ensuring they don't die.

[RobertISaar]

the backup tune is intended for stock injectors and the ONLY differences are with the backup, you're running SLIGHTLY less advance(roughly 2.5* everywhere), the lower peak boost, and of course the injector vs EGR table is setup for the stock injectors... if you run the normal tune with the injectors you just got ahold of, it SHOULD run correctly... if not, and you run the backup tune, it is going to run rich until the O2 corrects for it.

[Penglii]

Thank you, that is what I imagined you did... but I wanted to be cautious and know for sure.

[RobertISaar]

safe >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> sorry

[Penglii]

Well now I might just be paranoid here... but way better safe than sorry, and I cannot really trust myself to think and/or diagnose anything clearly and accurately after this long week and weekend all without anywere near enough sleep.

 

So anyway, I got the new (probably 26#) fuel injectors in and the car all buttoned up and running on the normal tune. Even after sitting all week and stuff she now fired up faster than ever and the misfiring sounds and feels like it's gone. The exhaust does not smell like fuel and there is no longer a fuel smell in the engine bay when the car is shut down. So I'd say that is a major success.

 

HOWEVER:

I have not tried taking her for a spin or let her idle even long enough for an idle relearn... because there are now grey jets soming out of the tailpipe. In the 20 or so seconds I let her idle, the jets were consistant and protruded like 5 inches out of both exhaust tips. I stuck my nose right up in one and it smelled only like normal car exhaust smell. The jets smoked up the air around me with moderately lingering grey smoke that dissipated with the breeze and of course still did not smell notable in any way.

 

What might be causing this?

 

Is it just smoke from the oils from my hands and the oil I lubricated the o-rings with and so likely to go away if I just let her run?

Or is she running super lean because of the new injectors flow rate being less exactly known than I hoped (I don't know what 'lean' smoke looks like, but I've heard it's grey).

Or is it because my oil needs changing from fuel leaking down into it?

Or maybe my o2 sensor has been ruined from the raw gas blowing past it, maybe if I replace that it will clear up?

 

*shrugs* Any thoughts on the matter would be greatly appreciated. Sorry for the long windedness... I'm brain fried for all kinds of reasons right now.

[RobertISaar]

IMO: let it run long enough to get the O2 sensor active, see what kind of fuel trims it's saying. if it IS running extremely lean, you'll also see a lot of IAC counts because a lean idle doesn't create a lot of vacuum.

 

i would also look at an oil change(winters coming anyways) if you suspect it is loaded with fuel.

[Penglii]

CLOSED LOOP DATAS:

These datas were collected with the engine at idle in closed loop using the 26# tune after a few minutes of idling.

IAC = 30

MAP = 38 Kpa, 0.80 V

Idle = ~800 RPM

Spark advance = 16*

o2 = 706 mV

Block Learn Cell = 0

Fuel Integrator = 76

Block Learn = 128

Injector Pulse Width = 0.3

 

Apparently Tech-1 does not tell me Injector Duty Cycle.... interesting...

[RobertISaar]

INT is 76? that's rich as hell(or at least the O2 thinks it is), probably against the INT low limit IIRC, i'd have to dig into the tune a bit.

 

injector duty cycle can be calculated fairly easily though, as long as you can capture

[Penglii]

Right on, I can capture and calculate.

Yeah, the INT concerns me... and the Injector Pulse Width seems low too... what might that mean?

[RobertISaar]

.3mS is ridiculously low... especially for 26 lb/hr injectors on a 3.1.... unless they're coming out to more than 26....

 

capturing the pulsewidth at the highest RPM and boost you intend to run will give you a good idea of how far they're being driven.

[Garrett Powered]

I was getting the same thing. trying to figure out a tune for 28# ls1 injectors. idling it would start smoking. it was hard to tell exactly what was causing the smoke because I started using a different turbo and a couple different tunes. one AZRC based and one TG160 based. the wideband was acting very different between the two during idle. AZRC based (I call it "workswith 28") for the injectors, would look like it would want to stay around 14.7 at idle, and the TG160 would slowly get richer and richer until it got to 9 or 8 afr. but then it would start smoking. first time I saw it smoke was on the TG160, but caught the other one doing it sometimes. it was very strange and confusing. for the last week or so it has been smoking less and less often though with "workswith28" in it. so something is going on internally to fix itself? I never considered that thing about lean smoke. I thought it was rich smoke or turbo smoke. I still dont really know. may be a combination of stuff.

 

I wanted to use the TG160 based one for it since parking lot driveability is smoother. the other one has bucking or surging type behavior under 20 mph sometimes and will stall once in awhile. although today I tried to datalog the problem and it wouldn't do it. no smoke or bucking.

 

I may go back to stock injectors if I can't get it where I want it with the 28's. they should be able to push enough fuel for a little bigger turbo. I don't know, tuning can be real hard on your engine so if you figure it out sooner the better. I am going to change my oil soon as well. I figure if I can tune the stock injectors to run good with this bigger turbo with the TG160 THEN try to change up to bigger injectors, it would be easier. thats if it idles at 14.7 afr like it should and doesn't smoke.

[Penglii]

Robert the main tune is the one WITHOUT the chip's wire grounded, correct?

Figure I should consider every possible thing...

[RobertISaar]

switch in off position, or not allowing the ground SHOULD run the normal tune... but hell, see what happens with the other tune.... it SHOULD run even richer, but you never know...

[Penglii]

I will check that tomorrow... but that must be correct because the car ran fine since August on the stock injectors with the wire grounded.

If the injectors were running 28# somehow... could that cause it to idle with the INT and Pulse Width I'm seeing?