After TBI to MPI conversion

[hirax]

Theme was started here:Engine rpm, mph, and lock up with A413
So I did the tbi to mpi conversion.
I use T2 intake with its fuel rail, pressure regulator and TB, Accel 15 pph injectors, fuel pump from 3ltr Ford.
During engine overhaul made some little mods: head milled 0,01” down, port matching, polished combustion chambers, 3-angle valve job, wintage tray.
Now it run, but with some problems.
I don`t feel, that engine have more power now and main problem with engine rpm.
Engine rpm fluctuates when car run freewheel (sometimes it even stalls) and sometimes when engine idles (on Park). Both events will arise when engine is warmed up. I also have a/f gauge and I noticed that when engine is warm the rpm start fluctuate with same speed as a/f gauge reading changes (about 3 times up-down per 2 sec). Feels like the engine is very responsive to changes of volume of fuel. First and easiest way was increasing fuel pressure by disconnecting vacuum from fuel pressure regulator. It helps, but not enough. Now I will try to change injetors to bigger size.

Quote:

Originally Posted by 90Shadow OH man, I'm surprized your transistor hasnt blown yet! Why don't you use the computer from a turbo and wire the extra injectors? Or even better yet, do a turbo conversion! Your halfway there already. Cool to hear you actually got it running though. I once thought about going your route.

I can`t understand why I must be affraid about injectors driver transistor. From Ohm`s law: current = voltage / resistance. Original tbi injector have about 1,5 ohm resistance and current throuhg circuit is 12/1,5=8 A. Now I have injectors by resistance 14,4 ohm each, connected to parallel they have common resistance 3,6 ohm. Current is 12/3,6=3,33 A. This is less than with original injector. Confirmation of this now I have alwas error code 26: „Peak injector current has not been reached”. Don`t confuse with code 27:„Injector driver control circuit open or shorted”.

Conversion to turbo or to turbo ecu is here in estonia pointless. Very hard to find used parts for this and when ordering from US, they will here pay too much. Easiest way is to buy a car already with turbo. Same thing there, I think

[hirax]

Quote:

Originally Posted by 90Shadow I would draw up a schematic of a circuit to take a reading of crank position and calculate when each injector should fire

Can you tell a little more about this idea?

[Rampage1967]

Something isn't right.
Do you have a good o2 sensor & not a really slow reading one??
Is you cam timing right??
What about your map & TPS, are they reading right??
Also, very advanced ignition timing can do things like this.
I also beleive that you need larger injectors. Try some 19 PPH ones.
My newly done one idles just like the TBI system did.

[daytonaer]

Fiddle with the AIS motor and the adjustable screw on the throttle blade, thats how I eventually evened out my idle. Remember, every time you make a change to the throttle blade to reset the computer, or it will be compensating.

(the way to get the ais to shut fully is to create a giant vacuum leak, ie unplug the brake booster. once you do that, unplug the wiring harness from the ais motor and shut off the engine, replug the vacuum line and adjust the throttle blade. once you get it to idle well with the ais fully closed, you can plug the ais back in. Sometimes it works to reset the computer after you do this, sometimes it doesn't. fool around with that.)

[Rampage1967]

I actually plug in my snap on scanner & access the "minnimum idle speed" function. Makes it a snap to set.

[hirax]

Thanx
Step by step it goes better and better.
Play with AIS and throttle blade made the engine more stable...
but not enough.
At least I got 19PPH injectors from 3,8ltr Ford. I put them on engine and now I like have totally another car It almost 100% ok.
Little rpm fluctuating at idle and by freewheel, but no stalling more
Small problems stays but generally the main trouble is gone.
At first I must find connection to measuring point of fuel pressure. Also I suspect that one of hydraulic lash adjusters not work correctlty (periodically little clinks and some misfires when idling)
Will keep on experiments.

[Rampage1967]

That's good to hear.
The more I drive mine, the better it runs.
Get i working right, you will love it. Mine has loads of power & great drivability. . . even in 10 deg F weather.

I'm running 27 PPH T1 injectors at 24 psi (formula says they flow same as 19 PPH 3.0 injectors)

Idle is unstable, but, that is LM problem on my car. It was that way with the TBI & there is a TSB on it. I can live with it till I ge t another LM.

Just to give some perspective on what seems to work, here's the rest of mine:

*1987 2.2 TBI engine . . . 130,000 miles . . . 150 PSI all cylinders
*auto trans with 3.02 gears, stock converter & 195/75R14 tirs
*88 TBI roller cam, advanced 5 degrees
*2.5 T1 manifold, ported (by me)
*3.3 L, 52 MM throttle body
* sensors for 3.3 throttle body
*TB temp sensor tapped into manifold
*adjustable regulator (home made)
*K&N cone filter (for now)
*Ignition timing set 12 deg

Do you have a 2.2 or a 2.5?? A 2.5 may need more fuel.
If you have a 2.5, try an adjustable regulator & up the pressurea bit, you still sound lean to me.
I guess I got lucky, mine worked on the first try.

[hirax]

Yeah I forgot, my car is 2,2 ltr Plymouth Sundance 88 with A413.
By a/f gauge it not run lean, reading is about 0,6-0,7.
In future I also plan make adjustable fuel regulator.

Sorry for stupid question, but what mean LM and TSB

[Rampage1967]

LM - - Logic Module (early style Mopar engine controll computer)
TSB - - technical service bullitin (repair bullitins isued by Chrysler on specific problems)

BTW, .6 - .7 is slightly lean wide open, ok part throttle. (.8 -.9 is good wide open)
I never have checked mine, I just kept upping the fuel pressure till it ran good wide open.

[sgtarky]

I got all my parts need, just need to figure out if I should use the turbo injectors or the ford injectors. I have both.

[DaytonaTurbo87]

Are you planning on firing the injectors off of the tbi electronics or the turbo electronics? If you were to use the tbi electronics, I heard the turbo injectors won't do. Something about their resistance. If you're using turbo electronics, then you're good to go with the turbo injectors as long as you also have a turbo spec fuel pump and regulator.

[sgtarky]

yeah I will use the tbi computer. Rampage did the same but he says he used the turbo injectors. the guy with a 92 daytona used ford injectors and has wiring diagram, however I wont use a terminal block, dont see a point in it. I bought ford injectors too. I tried to get in contact with rampage to find out how he wired his injectors.

[Rampage1967]

I wired them in parellel. The car has been running great every since.
I'm actually using 24pph early 3.3 injectors but they are still 2.0 ohm.
Fuel pressure is set at 38 psi on E-85.

[sgtarky]

so you just basically spliced the turbo fuel injector harness into the stock tbi injector harness......vs what the other guy did by making a terminal, which I have no idea why he did that. gotta post pics dude. I got my parts painted up too. I ground down the "turbo" on the valve cover , painted it orange. I will sand the fins and chrysler down so they will have metal finish. I will post pics of it this weekend.

[Rampage1967]

I used the sheet metal valve cover & spliced the wiring right in. It looks like an old stock setup of some sort with a cone filter on it.