Alfa Romeo Tuning With The Dynograph

I wrote this article in 2000 about work I did on my car. Your car and experience may differ, proceed with caution and at your own risk.

The Dynograph is a small meter with LED’s that reads your engine’s fuel mixture with the aid of an O2 sensor. The size is similar to a radar detector and is totally unobtrusive. If you like tuning your car, try one. They are easily used on all cars for tuning purposes from carburetors, to SPICA, and to EFI. Use on an EFI system may be limited to the changeable parameters on your system (you can trick an EFI system to run rich by installing a resistor in the EFI coolant temp sensor circuit for example).

Essentially, in theory, at Wide Open Throttle (WOT) under load (hard acceleration, up a hill etc) and above 4000 rpm the “middle amber” on the Dynograph should be lit up for a SPICA injected car to achieve a “perfect” fuel mixture across the entire rev range (per Wes Ingram)! Wes sells the Dynograph as a complete kit or in separate components.

To start, call Wes Ingram to get your Dynograph, and at the same time get one of his SPICA injection manuals. If you don’t already have the factory SPICA manual and AROC’s SPICA manuals I’d highly recommend you have them on hand! The cost is approx. $20 for each of these manuals. You can obtain the AROC manual from their website (or call them) and the factory manual from a place like Centerline or International Auto Parts.

Let me say right now that Wes should sell an “extended service contract” for the Dynograph. Wes so helpful with every e-mail and phone call I made (and personal time at the National Convention) to help me interpret the LED display under certain loads and conditions. All at no charge! I’m sure he must get tons of inquiries all the time for all his services. I really appreciate all the time he spent with me as I feel it greatly enhanced the driveability and fuel economy of my car!

Wes should be able to advise on the expected LED readings you’d see on your specific application (car, engine, modifications), and at running conditions (best RPM, etc.).

Make sure your car is in tune – new plugs, cam timing correct, valve clearances correct, SPICA (or carburetor/EFI) settings like rods and butterfly’s correct. Follow the manual instructions to make sure all the SPICA gaps and Thermostatic Actuator are functioning correctly. Make double sure your butterflys do indeed achieve Wide Open Throttle (WOT) with pedal on the floor.

Installation was a snap – simply install the O2 sensor, wire in the Dynograph and you’re set! The instructions to install the O2 sensor say to use XX size drill bit, drill hole, and braze on the fitting. Well, I simply went to a little muffler shop I’ve had some cutting and bending done at before whereby they used a cutting torch to put a hole where I wanted, and brazed on the fitting for $20. The mounting place I chose on my ’72 spider was right where the two headers come together at the front baffle/muffler. I used a Dremel tool to cut a half moon shape out of the combo skid plate/brace (facing the ground) at this juncture to clear a space to braze the fitting (can’t get to the pipes there with the plate in place) and had the O2 fitting mounted facing toward the outside and downward just enough to clear the frame rail (but not sticking down below the muffler). They made sure the sensor extended properly into the exhaust flow as well. The O2 installation was the hardest part of the entire installation!

I used terminal connectors for my wire job so I could remove the DG3 when not “tuning” the mixture, even at the O2 sensor so I could remove it as well (putting a threaded plug in it’s place). I used small Velcro pieces from a hardware store with sticky-back to place the DG3 on the left side of the dash.

The fun part is tuning the fuel mixture! Previously, I’d set the mixture using a gas analyzer at idle and at 2500 rpm to get an appropriate mixture per the factory SPICA manual (the part that’s in the AROC book/manual) and Wes’s SPICA manual. Note – all my testing was done at the N setting (at 70 degrees F too).

Here’s where my phone calls started…with the DG3 the mixture immediately showed as rich under full WOT. Rich is the far right amber, middle amber best, left amber the leaner side of rich but still OK. Green is too lean for a SPICA car (but will show on EFI cars and its OK since they’re designed that way). Red is definitely way too lean – stop the car NOW and revise fuel mixture. Mine was all the way right – full rich at WOT.

Q: “What’s WOT?” Wes Ingram: “Foot to floor – all the way to the floor”. Turns out the last ½ inch or so of pedal travel moves the SPICA internal cam to a “really rich for go fast juice” mode. You’ve got to set the mixture at middle amber in this mode it turns out, to get the proper mixture across the entire rev range.

Q: “What if it flickers a bit at the far right at WOT with middle amber still lit?” WI: “It’s OK if it goes out instantly, it may stay on a while if you’re in too low a rev range – it reads more accurately above 4000 rpm, the SPICA internal cam will be in the proper location rev-wise. Above 4000 rpm it’s OK if the LED just flicks into right amber an instant as long as the middle amber is lit.”

Armed with the above – I quickly found the “correct” mixture by turning in (leaning) the fuel cutoff solenoid one notch at a time – until at almost ½ turn leaner the middle amber was on at WOT above 4000 rpm, with an occasional flicker into the right amber with middle still on. My fuel mileage increased a bunch, less color out the tail pipe, and starts/runs better than ever under all conditions.

Another note – earlier in the year I thought I had a dirty check valve or cracked injection line, except no fuel smell or residue on the injection lines because at cold start after sitting overnight the car would stumble a bit upon startup even with the cold start solenoid set at 150rpm drop. Turns out the mixture was pretty rich, so was causing just enough flooding when cranking to cause a slight stumble before burning off. Now theses symptoms are gone.

Following Wes’s advice, I left the setting alone (yes, that’s right, no more fiddling) to observe how the lights/mixture reads under different conditions. After driving under various loads and roads, the lights still show up the same under the same conditions, up hill and dale, coast or valley, fast or slow, WOT and not.

I find the left amber lit under most conditions (what Wes described as “light cruise”, for example on a freeway, at 60mph with throttle just cracked), with heavy to WOT resulting in a lighting of the middle amber, with an occasional flicker to the right.&

Wes also noted that I might get a left amber at idle which approximate 2% O2, but is dependent upon ignition advance (more advance may induce a higher % O2 at idle, thus left amber may not be achieved). I mostly have middle amber at idle, but occasionally get left amber, more so as the temp gets close to 55 degrees F (denser air, leans mixture out a bit).

It’s neat to see the effect of mountains etc, you can practically see the barometric capsule and clip at the back of the pump compensate – very quickly. I’ll say that the DG3 senses the mixture with absolutely no lag whatsoever, press or lift off the throttle and the lights flick right or left instantly. \

I removed the DG3 when I was satisfied all was working as intended.