Are my injectors too big?

[Dusty_Duster]

I put a set of "804" injectors in my '88 2.2 Turbo I, thinking they were the stock injectors. Apparently, I was supposed to use the "803" injectors instead, which are slightly smaller. Now, I've lowered my fuel pressure by 5 psi to account for this mistake. The car seems to run just fine, but according to my narrow-band A/F gauge, any time I'm above 4 psi of boost, I'm running rich (as in the last two lights are the only ones lit up).

I'm running a front-mount intercooler, g-valve set at 12 psi, and other goodies.

Should I be concerned, or will it be OK to drive the motor until I can get it tuned?

[Frank]

That could explain it. Check out http://www.turbo-mopar.com/forums/vbarticles.php?do=article&articleid=20

[Dusty_Duster]

According to that chart, the stock '88 Turbo I injectors are 27#, and the "804s" are 36#. Jeez. I increased the flow by 33%.

I could turn down the fuel pressure some more, but I'm rather worried that the motor would become difficult to start.

[badandy]

According to that chart, the stock '88 Turbo I injectors are 27#, and the "804s" are 36#. Jeez. I increased the flow by 33%.

I could turn down the fuel pressure some more, but I'm rather worried that the motor would become difficult to start.
I had them (804's which are TII equivalent) in my CSX-T by mistake. Lowering the fuel pressure should not cause an issue but will you have enough adjustment room to make up the difference?

[cordes]

It really should not be that big of a deal. I thought that the general consensus was to use the 803 and 804 injectors as stock replacements for their respective applications, as they really did not flow what they claimed? I would think that the computer would be able to compensate for them when in open loop, and they probably won't be that rich (if at all) at 12-14PSI on a relatively stock cal I would think.

[badandy]

It really should not be that big of a deal. I thought that the general consensus was to use the 803 and 804 injectors as stock replacements for their respective applications, as they really did not flow what they claimed? I would think that the computer would be able to compensate for them when in open loop, and they probably won't be that rich (if at all) at 12-14PSI on a relatively stock cal I would think.
The computer cannot compensate for a 33% flow increase without reducing the fuel pressure an equal or near equal percentage.

[cordes]

The computer cannot compensate for a 33% flow increase without reducing the fuel pressure an equal or near equal percentage.

So you are saying that those injectors do flow that much.

[butchsuppe]

Recently I talk to an aftermarket fuel injection engineer at work about adjusting fuel presure, told me to lower pres. until the motor begins to stall than adj. it to a smooth idle. Just like a carburetor he said, made sense to me so I tried it. Seems to work good as the plugs look good.:nod:

[Dusty_Duster]

The reason I'm talking about the hard-starting issue is that I used to have the +40s in there. I turned the fuel pressure waaaaaaay down (to around 25-30 psi) to keep the engine from flooding. The car was very hard to start, though. However, since then I've replaced a defective AIS, so that might have actually been the problem.

Hmmmm, I still have those +40s sitting in my garage...

[badandy]

The reason I'm talking about the hard-starting issue is that I used to have the +40s in there. I turned the fuel pressure waaaaaaay down (to around 25-30 psi) to keep the engine from flooding. The car was very hard to start, though. However, since then I've replaced a defective AIS, so that might have actually been the problem.

Hmmmm, I still have those +40s sitting in my garage...

I doubt that was your problem...it was the fuel pressure...

You have to remember that (when you reduce fuel pressure that much) that you are cutting the stock pressure almost in half! The system is designed off of pressure and duty cycle...it's a leverage between the two for proper fuel flow. Take for instance: If you kept a stock injector in and you started to reduce pressure you would have to increase duty cycle to maintain the same amount of fuel flow. You are wanting to increase the injector orifice while trying to use reduced pressure to balance out your fuel needs. It will become increasingly difficult to pressurize the rail when 4 injectors with a large orifice are constantly opening. You can see where it might be difficult to keep the fuel rail pressurized under these circumstances...and of course the spray pattern will be sacraficed.

[ShadowFromHell]

I think dropping the fuel presure 5psi was the thing to do. I use to run a 88 Shadow ES (same drivetrain as your CSXT) and ran the stock ECU, with +20's and a 2:1 RRR with a adj FPR. When I swapped to a T2 computer (which I HIGHLY recomend, much more power) I had crank the base pressure up 5psi to get the car to run right, because the stock t1 ecu was designed for 27pph injectors, and the T2 was set up for 33's.

So if you have dropped the base pressure 5 psi, I wouldnt worry.

[mock_glh]

Did the '88 T1's really use 27# injectors?. I thought all of the "blow through" engines used 33#. I guess because it was still a 2.2? :confused:

[Dusty_Duster]

Did the '88 T1's really use 27# injectors?. I thought all of the "blow through" engines used 33#. I guess because it was still a 2.2? :confused:

Well, see, now we're getting to another part of my problem. The engine I have came out of a '90 Dodge Shadow, which was (allegedly) equipped with the Turbo I and an automatic transmission. However, the guy that did the engine swap for me (since I didn't want to mess with the wiring), said that the motor was actually an '88. But the chassis was definitely a '90, because it didn't have sealed-beam headlights and had the newer-style taillights and interior. :confused:

So you can tell I was (am) quite confused by all of this.

Anyway, my car seems to be running just fine. There is no smoke, and I've driven around for several months like this without any problems (other than the aforementioned AIS motor.) I'm also using Denso Iridium plugs with a full MSD ignition system, so I'm guessing my spark is plenty hot enough to burn off small amounts of extra fuel. (But my fuel economy does suck.)

If I were to get a FWD Performance calibration (I'm thinking of a Stage II), would it be able to handle the extra fuel put out by these injectors?

[turbovanman²]

You can safely turn down the injectors to roughly 20 psi and not have any starting issues. If you have issues, its not the injectors. The way I set larger injectors is to go to WOT and dial out fuel until your at your desired AF ratio. This will then enable the computer to stay in closed loop out of boost and keep your fuel economy up. Sometimes this can make closed loop a bit lean so you just add a bit more fuel pressure.

[Dusty_Duster]

So if I'm under boost at all, I won't be in closed-loop? Because if I'm not under boost, my A/F gauge does the dancing lights thing. And under boost, I usually get the third- or second-to-last light lit up...

[turbovanman²]

So if I'm under boost at all, I won't be in closed-loop? Because if I'm not under boost, my A/F gauge does the dancing lights thing. And under boost, I usually get the third- or second-to-last light lit up...

Correct, hitting boost, I believe its 2 psi or more, the computer goes into a preset table, this is why changing the fuel pressure affects fuel in boost, the computer doesn't adjust it.
When out of boost, the computer uses the oxygen sensor to trim the fuel for fuel economy and to light off the cat.
If you fuel economy is good and its dancing at cruise, your all good, :thumb:

[MiniMopar]

OK, if the '88 t1 was put into a '90, they would have had to swap in the 34.85# injectors. Since there was no '90 2.2L cal besides the VNT, they were probably using a 2.5L T1 cal. So the question is: what electronics are you running now? If your ECU is an '88 T1 SMEC, then it expects 27# injectors. The corrected pressure would be 33psi of base fuel pressure.

[GLHNSLHT2]

is it a commonblock? Might want to check the date stamping on the back of the block. If it's a 90 2.5 motor you'll want to keep the 804's at stock pressure (the 804's are stock size, the 803's were 30lbers) and find a 89 2.5 Turbo 1 smec to run the car. It'll bolt in.

If it's not a commonblock and the date says 88 on the back of the block then you probably have a 2.2 motor. Keep the injectors and find a 88-89 2.2 Turbo 2 SMEC and plug it in.

[Dusty_Duster]

Correct, hitting boost, I believe its 2 psi or more, the computer goes into a preset table, this is why changing the fuel pressure affects fuel in boost, the computer doesn't adjust it.
When out of boost, the computer uses the oxygen sensor to trim the fuel for fuel economy and to light off the cat.
If you fuel economy is good and its dancing at cruise, your all good, :thumb:

Awesome. I'm getting like 16 mpg around town with the boost set at 12 psi. That sound reasonable?

[TurboJerry]

This may be hard to believe but I calculated 35 psi fuel pressure if you run 36 pph injectors on a 27 pph '88 2.2 T-I cal. (if you want them to be the same flow rate) I would look for the fuel pump block off plate on the block to see if it's a 89+ engine. And if it is *not* there, then pull a spark plug to look for the huge piston dish to show if it's a 2.5L. If it has a *factory* oil drain tube on the block for the turbo, it's most likely a 2.5. I've run 2.5 turbo computers + injectors on '88 2.2 turbo's and they did remarkably well. I don't recommend a T-II computer unless you're putting an intercooler on it. (It will spark knock itself to death)

[turbovanman²]

Awesome. I'm getting like 16 mpg around town with the boost set at 12 psi. That sound reasonable?

Thats low, my pig van got around that, guys brag on here about getting 20+ mpg and even 30.


This may be hard to believe but I calculated 35 psi fuel pressure if you run 36 pph injectors on a 27 pph '88 2.2 T-I cal. (if you want them to be the same flow rate) I would look for the fuel pump block off plate on the block to see if it's a 89+ engine. And if it is *not* there, then pull a spark plug to look for the huge piston dish to show if it's a 2.5L. If it has a *factory* oil drain tube on the block for the turbo, it's most likely a 2.5. I've run 2.5 turbo computers + injectors on '88 2.2 turbo's and they did remarkably well. I don't recommend a T-II computer unless you're putting an intercooler on it. (It will spark knock itself to death)


Yep, your right, mid 30's would be correct, :D

[TurboJerry]

Thats low, my pig van got around that, guys brag on here about getting 20+ mpg and even 30.

I get 24 mpg with my "piggy" van hehehe....... It will probably get worse with the intercooler DOH!!!!!

[turbovanman²]

I get 24 mpg with my "piggy" van hehehe....... It will probably get worse with the intercooler DOH!!!!!

Grrrrrrrr, :censored: :p

Auto or standard?

[GLHNSLHT2]

He does have an i/c I thought. But yes only the T2 puter with an intercooler. As far as MPG I get 32 around town and 37+ on the freeway. Simon your van sucks :)

[cordes]

Awesome. I'm getting like 16 mpg around town with the boost set at 12 psi. That sound reasonable?

that is some really low MPGs. If you are not on it all the way through every gear at every stop light, there is a problem. What vac are you pulling at idle? Also, pull the plugs and see how they look.

[TurboJerry]

Grrrrrrrr, :censored: :p

Auto or standard?

It's auto. I can't see converting it to a 5-speed since I've been so close and personal with the auto's for so many years. :eyebrows:

[Dusty_Duster]

Car is an auto. My vacuum at idle is 10 inHg, around 20-22 inHg during deceleration. I have high-profile "Enforcer" cams from FM, so that explains the low vacuum (I think). Checking the pistons won't work; I have aftermarket forged pistons.

I need to figure out what engine I have, because now I'm thinking the computer might be for the wrong year. You said to look at the fuel-pump block-off plate? Where would that be? Got a pic?

EDIT: If you want the full-specs of the car, go to my cardomain site:
http://www.cardomain.com/ride/310854/5

[Speedeuphoria]

My vacuum at idle is 10 inHg

Thats a problem, not good at all. Your cam timing is prob off

[Dusty_Duster]

Thats a problem, not good at all. Your cam timing is prob off
It's always had that low of a vacuum. I thought the cams could cause that?

[cordes]

It's always had that low of a vacuum. I thought the cams could cause that?

they certainly can. I know of one guy who was still pulling between 12 and 14" with a Taft stg. III in his car though. 10 sounds really low. i wish I had a vac gauge on my car when I had the FM505 in it. I would certainly double check the cam timing. You should probably degree it to see what is going on there if you haven't yet.

[Dusty_Duster]

I've started a new thread about the vacuum issue:

http://www.turbo-mopar.com/forums/showthread.php?p=191632#post191632

Thanks for the help on the injectors!

[88_pacifica]

Bump this thread for another quick question. What's the next step up from the stock T2's? I keep seeing the random pph's so I'm not "quite" sure, but I need the 36 pph's(803 or 4's?) I think. Where can I get these or does anybody have a good working set they want to unload? I have a freshly rebuilt set of T2's, but one leaks though, so I figured that now is as good a time as any to step it up.. TIA!

Nate

[turbovanman²]

Bump this thread for another quick question. What's the next step up from the stock T2's? I keep seeing the random pph's so I'm not "quite" sure, but I need the 36 pph's(803 or 4's?) I think. Where can I get these or does anybody have a good working set they want to unload? I have a freshly rebuilt set of T2's, but one leaks though, so I figured that now is as good a time as any to step it up.. TIA!

Nate

The next step Mopar wise is the +20's. I might have a set if they ever show up the guy I bought them from.

The FAQ and KC center has a breakdown of the part numbers.


I totally agree, 10 inches is way too low, I don't think there any cams out there that are that wild to cause 10 inches. I would recheck your cam timing.

[88_pacifica]

Thanks Simon, I will check that. However, the +20's will definitely require me to use the RR reg and AFPR and I'm not REALLY wanting to do that yet. I am going to be on the stock cal(2.5) and only at the max(14.7) of the stock 2 bar. I have a .020 overbore and slight port on the intake and exh mani's, Garrett T2 with the midget 2.25 SV for now. :( I plan on eventually doing the exh(stock Mitsu 2.25 w/stock exh). I got the stuff to get the IC here when I get around to it and I will do it before too long....

I'm just a touch lean with the stock 2.5(T2) 33ph injectors(1625-50*) and I figure the 80- somethings should be fine and will offset the "slight richness" once I IC it. Not looking to go crazy, just trying to stay stockish to 14.7#'s. I think the +20's "might" be a bit much. Don't really want to lose gas mileage though either here, since that's why I got the Dodge in the first place. What do you think guys? Are +20's REALLY necessary?

Edit: Here's the proposed winner from the KC?

P4452804 ___________ 36pph _________ 13% Mopar Performance

[turbovanman²]

Well the 2.5 or TII injectors are rated at 32, so yeah, the cc's of the R/T ones might do the trick. The other alternative is buy an AFPR and turn UP the fuel pressure. I have a set of RT injectors for sale! :eyebrows:

[88_pacifica]

PM sent...

[Dusty_Duster]

...
I totally agree, 10 inches is way too low, I don't think there any cams out there that are that wild to cause 10 inches. I would recheck your cam timing.

Cam timing is perfect. Ignition timing is perfect. I don't know what else to check.

[sdac guy]

I replied in your other thread, but will post here also for convenience sake.

If it is an aftermarket cam, then checking to make sure it is installed straight up (which is probably what you did) is of little use. If the person that installed the cam originally did not degree it in to it's centerline, then the sprockets can all be aligned properly but the cam could still be off enough to cause the problems you are having.

To properly check it, you need a degree wheel you attach to the crank pulley, a pointer of some type to reference the degree wheel as the engine is rotated, and a dial indicator to measure valve lift. But most importantly, you would need the specs for the cam indicating the proper installed centerline. I suspect you had none of these when you checked the cam timing.

Depending on the cam itself, that could be the source of the problem though. The Mopar Performance turbo cam with the part number ending in "314" has enough overlap in it's design that it has a low vacuum no matter what installed centerline is used. And low vacuum will lead to increased fuel use as the engine controller looks at vacuum to tell if the engine is under load. The lower the vacuum reading, the more it richens up the mixture.

That particular MP cam also has a narrow powerband which starts at about 3300-3500 rpm. So the cam design can cause the problems you are having such as low vacuum, poor mileage, and no low end torque. But so can having a cam installed at the wrong centerline.

Since you don't really know which cam is in your car (FM sells a few different ones), your best bet would be to get an adjustable cam sprocket and try different settings, advancing and retarding the cam slightly to see where your best idle vacuum is, and where the car runs the best overall.

Barry

[Dusty_Duster]

I replied in your other thread, but will post here also for convenience sake.

If it is an aftermarket cam, then checking to make sure it is installed straight up (which is probably what you did) is of little use. If the person that installed the cam originally did not degree it in to it's centerline, then the sprockets can all be aligned properly but the cam could still be off enough to cause the problems you are having.

To properly check it, you need a degree wheel you attach to the crank pulley, a pointer of some type to reference the degree wheel as the engine is rotated, and a dial indicator to measure valve lift. But most importantly, you would need the specs for the cam indicating the proper installed centerline. I suspect you had none of these when you checked the cam timing.

Depending on the cam itself, that could be the source of the problem though. The Mopar Performance turbo cam with the part number ending in "314" has enough overlap in it's design that it has a low vacuum no matter what installed centerline is used. And low vacuum will lead to increased fuel use as the engine controller looks at vacuum to tell if the engine is under load. The lower the vacuum reading, the more it richens up the mixture.

That particular MP cam also has a narrow powerband which starts at about 3300-3500 rpm. So the cam design can cause the problems you are having such as low vacuum, poor mileage, and no low end torque. But so can having a cam installed at the wrong centerline.

Since you don't really know which cam is in your car (FM sells a few different ones), your best bet would be to get an adjustable cam sprocket and try different settings, advancing and retarding the cam slightly to see where your best idle vacuum is, and where the car runs the best overall.

Barry

Wow, thanks. That helped a lot. The cam was installed by the previous owner of the engine. He said it was from FM, but he was such a crackhead I have trouble believing anything he says. :lol:

I'm thinking of getting a stock cam and putting it in. That should fix all the problems, since I can be sure that it's timed correctly using just the timing marks, right?

[Dave]

Your A/F will be rich at part throttle in the boost. If it weren't you could run the risk of running too hot a charge. If you're really concerned hook up an oscilliscope and look at the duty cycle at higher RPMs.

[sdac guy]

Wow, thanks. That helped a lot. The cam was installed by the previous owner of the engine. He said it was from FM, but he was such a crackhead I have trouble believing anything he says. :lol:

I'm thinking of getting a stock cam and putting it in. That should fix all the problems, since I can be sure that it's timed correctly using just the timing marks, right? Yes, stock cams are installed using just the marks and aligning them per the manual when the engine is at TDC. Also called installing the cam "straight up".

If you switch to a stock cam, when you remove the cam key which keeps the cam belt sprocket from turning on the cam, be sure to look at it to make sure it is smooth and there is no "step" you can see or feel on the sides of the key. For centerlining a cam, either adjustable sprockets or offset cam keys are used. The offset keys have a very small step in them which allow the cam centerline to be adjusted in relation to the cam belt sprocket.

For a stock cam install, you certainly do not want an offset key, if one was originally used on the cam you have.

Barry