Correct injector for E85
 

Hi. I have a 94 metro xfi and would like to convert to E85. I need to find some compatible throttle body injectors I can use to get the right mixture. Later, I plan to increase compression with new pistons, but for now will work with stock engine.

Can somebody help with this?

If you are going to run E85 exclusively, you want injectors about 30% larger than stock. If you plan to use either E85 or straight gasoline some tuning will be required.

Also check that your fuel lines are compatible with E-85.

In theory your pump must be E-85 rated as well, but I "THINK" most pumps work just fine with E-85.

I can envision a $10 circuit (per individually fired injector) that would lengthen an injector pulse by 30% at the flip of a switch. If I were more of an ethanol fan I'd run off and try it.

As far as extending the pulse width goes, I think there are reasons to not have the duration of the pulse too long. Likely it would be fine, but I thought it would just be easier to have an injector with sufficient capacity.

I have heard estimates anywhere from 15% to 50% increase, but are all throttle body injectors alike and interchangeable? I need to know how to find one that will fit. Can I pull one off an old cavalier or corsica? I don't think I can go to the junk yard or the parts store and say I want an injector with 30% higher flow rate.

I'm aware of the lines issue, and will check that no rubber is in the line. Does anyone know if I will have enough fuel pressure and volume, or will I need a supplemental pump and new regulator?

I have never worked on TBI, but I can tell you that 95% of port injectors fall in to 2 categories Top Feed or side feed.

So do they mount and connect the same? Even different brands? Would something off a 1.8 or 2.0 liter engine be suitable? Any recommendations? I thought Bosch, ND, Delco, etc. would all have unique mounting and connection harnesses. If they are the same, that would make life easier.

All fuel injected vehicles after 1990 have fuel lines compatible with E10 and therefore E85. The quick and dirty way to check is pull a bit of fuel like off a similar car at the JY and store it in a jar full of E85 for a month or so.

Instead of messing with the injectors or pulse-width, just increase the fuel pressure. My stock pressure was 36 and at 65psi I can run E85 with no issues. Do not go above 65psi however as that is the generally accepted upper limit for injectors.

In terms of tanks and fuel pumps, you shouldn't have to do anything. I converted a '94 Acura Vigor with 200K miles on it. Been running E85 for a year with no problems.

2 things
1) TBI runs at very low pressure (like 10psi.
2) Injectors do hit a wall on running higher pressures, some more than others.

Okay, good to know. The theory would still hold true. If your stock pressure was 10psi and you wanted to increase your fuel flow 30% (for E85) then you would need your fuel pressure to be 17psi, which the TBI injector should not have a problem with. For flowrate vs. pressure calculations, to increase the flow rate by 30% you need to increase pressure by 70%. So, bottom-line, take your stock fuel pressure, and multiply it by 1.7 to get the fuel pressure needed to run E85. You can definitely get away with less, as the O2 sensor and ECU will pick up the slack, however for cold starting (open loop running) it's better to go with the 30% flow increase. I was running ~17% flowrate increase for a few months with no real problems, however when I bumped it up to ~30% increase cold starts were much smoother.

Here's a thread that long and tedious but there is some good info in there.

Its a lot easier to change a TBI injector instead of FPR or varibla FPR.

Sorry about bringing up this old topic. But with e10 gas price of 1.6e/liter (about 8$/gal) and e85 price of 1e/liter (about 5$/gal) e85 seems to be good option.

I have to be able to use normal gas in winter so I think that injector pulse extender is the best way of using e85? I am not really worried about extending pulse width too much course stock rpm limiter is set to about 7000rpm and I rarely exceed 3500rpm, if stock injector can handle full throttle 7000rpm with pure gas they can achieve 3500rpm with e85.The car in question is 98 toyota corolla with 1.6 liter 4afe engine.

I have good understanding of electronics so I have been thinking about couple of ways to make my own pulse extender. But I would be very interested about what dcb:s circuit is like, and if anyone has any ideas, circuits or even better circuit board designs?

Any other thoughts are welcome also.

For most cars with an oxygen sensor, I don't think extending the injector pulse or increasing fuel pressure is the entire solution. The fuel computer is going to try to close the control loop using the O2 sensor, and it won't read correctly using E85 - the computer is going to retract all the trim and you will end up too lean.

Probably depends on the vehicle, but forget about running closed loop for the best economy.

Yes, car runs on closed loop. O2 sensor or lambda sensor will work just as good on alcohol as on gasoline. It measures lambda value and lambda value 1 is best for emissions (not necessarily for economy) with gasoline or with alcohol.

So engine computer in closed loop will still correct properly using E85, provided you increase the fuel flow? Does it not depend on what cruising/closed loop mixture the computer is driving? Perhaps the differences are minor enough to get an efficient burn...

Interesting.

Yes in closed loop computer is always calculating long term and short term correction parameters. If lambda says engine is running rich short term parameter is degreased and when short term correction is below 1 long term correction is also lowered but with slower speed.

Injection time is calculated in closed loop (simplified) original_injection_time*long_term_correction*short _correction
Injection time in open loop is (simplified)
original_injection_time(which is different than in closed loop)*long_term_correction

original_injection_time is the parameter that takes into account all the other parameters that ecu takes into account

But problem with e85 is that the long_term_correction parameter is getting larger than its maximum value and ecu thinks there is a problem in fuel injection system.

This is the easy way. And the specifics are to put a fuel pressure gauge on the line at the injector, and adjust or replace the regulator.

Often you can unhook the vacuum line signal to the regulator (unplug the vacuum line) which raises the fuel pressure at idle and cruise.

From there, start adding E85. You will find the happy limit pretty easily. If you add too much E85, the check engine light will come on, but the car will continue to run fine (assuming 96 or newer and OBD2). If you have an older car, the car will accept quite a bit more E85, but eventually it will start to cough, have a hesitation, or generally act crabby. At this point you have reached "too much E85" and you will have to add 5 or 10 dollars of E10.


Also, most cars run FINE on E10. To change to E85 is less then 20 percent diffference, not the 30 percent quoted above.

I have thought about just increasing the fuel pressure but if I understand correctly increasing the injectors flow 23% would require 50% increase in fuel pressure. Stock fuel pressure is about 40psi over manifold pressure. Would injectors handle 60psi of pressure?

Car is 98 Toyota corolla with 1.6 liter engine. It’s not American model and it doesn’t have obd2

Just start blending and see what percent you can run until a check engine light comes on. Running 28% in Stratus, last tank was 21, I think 44 was the highest I've ever went yet.

http://www.rhapsodyingreen.com/rhaps...evel_study.pdf

unhook the vacuum line to the fuel pressure regulator.

50 percent is doable in most cars.