2seater

The mileage range sounds about normal, although steady highway speeds shouldn't be in the teens. As the % of alcohol is increased in normal gasoline, the mileage will drop by some amount. Same fuel stops? What is the actual mileage calculated from usage vs measured miles? I have owned more than one Taurus/Sable and the normal fuel mileage has been similar to my Reatta. I doubt the Merc weighs 1k pounds more than the Reatta, unless you are comparing the gross vehicle weights on the door, which includes cargo and passengers? The Reatta weighs more than a LeSabre of the same year, but has a very limited load capacity.

GM did turbocharge 3.8's for more than ten years before the Reatta, although not in the 3800 iteration. Good question about the factory experimentals they did, and it is unfortunate they apparently did not survive. The downside to the S/C engine, (if there is one), is it didn't exist before the Reatta terminated. My personal opinion is that it is a logical upgrade if the model had continued so it is actually a prototype ;-)

IMHO: Better, yes. Original, no

Dave, Thanks for the offer, but I have several MAF's as well, all tested on the flowbench. Padgett, I have the original equipment MAF sensor in place, although I do have an "L" (snakes) sensor in my collection as well. The "L" sensor looks the same from the outside but it is different where it inserts and cannot be interchanged into the "C" housing. However, the "C" will install in the "L" housing, although I don't know how accurate it would be since the flowpath at the sensor would not be smooth? In any case, I believe I have corrected the problem, although not certain of the cause? I noticed the problem got worse with the larger throttle body, coupled with the larger plenum on the intake. My surmise was this combination somehow affects the flow through the sensor portion of the MAF assembly. Even though timed acceleration runs were slightly faster with the larger T/B, the MAF read about 7% lower (same sensor). I had constructed an adapter to allow location of the stock MAF housing to the inlet side of the turbocharger. I transferred the same sensor to the remote housing and coupled that upstream of the stock setup. It took a little driving but the BLM has dropped to 130 at the same 70 mph cruise and it moves around slowly in the expected range. The original question was I suspected the calibration of the various cells in the PROM was different but I think now that my modifications have caused it to read a different cell than the ECM expects. I will know if the operating cell has now changed when I get a chance to drive it with the scanner connected. Should have done so today but I didn'g expect such a large change. Thanks guys.

Follow up: I changed the O2 sensor but it operates exactly the same. Cross counts look good, 70 mph cruise shows high teens to over 20. Integrator still looks good. Runs very well overall, but blm sits @ 150 while cruising. Roll into the throttle a little and it drops to 149, so it isn't stuck there, it just wants to be there. Will check for vacuum or exhaust leaks again. Going to try my remote mount MAF to see if it the operation changes. Thanks for the suggestion.

Greg, Well, I have seen readings that high before but only when fiddling with the tuning when turbocharged. I do not have a spare ECM or stock chip, although I have a few different turbo tunes. The chip is a copy of the stock ANWU, but it is not the stock EEPROM. I have a zif socket installed to reduce the cost of chip programming. A flaw in the copy? Padgett, Good idea on the O2 sensor. I do have a few others so I will try switching it as suggested. The tailpipe is black although it doesn't smell too bad even without a cat. When I swapped back to the stock engine I did find I had blown the vacuum modulator and it has sucked down over a quart of fluid over some time. I have several hundred miles on it after the switch and repair, so I would think that residue is no longer present. Thanks for the replies. I was guessing the slightly more aggressive cam has affected where the ECM is running as far as load cells go?

Does anyone know if there are ECM programming differences between the 1988 and 1990 model years, specifically relating to the fueling in the (16) operational cells? The reason I ask is the BLM is stubbornly stuck in the high 140's to 150 in all cells, although the Integrator is operating in the normal range. This is my stock 1990 engine with the 1988 cam installed. The only other modification is a larger plenum on the intake manifold. I have tried both the stock throttle body and the 0.2" larger diameter one with the same MAF sensor installed and it is slightly worse with the larger throttle body. Raising the fuel pressure to 46# did help slightly. It acts like it wants larger injectors, but the engine is otherwise bone stock. Stock manifolds, ceramic coated, rear outlet opened up, no cat. and straight through muffler. Idle vacuum is good at a steady 18", O2 sensor is good and active, overiding the injectors individually yields similar vacuum and rpm drops. The engine runs very well overall, starts instantly and cruises easily. Any thoughts?

What is the IAC doing while it lopes? Is it cycling up and down to try to cover up for something else? I assume no codes apparent? The tap test on the MAF as Dave suggested is a good place to start and you can disconnect almost all sensors and start the engine to see if one of them is sending a bad signal. If you have a reasonable idea of what the idle readings should look like, you can cycle through the ECM data while idling to see if something looks amiss. Was the battery disconnected while you were away?

Simple to check the incoming air temperature in diagnostics to see how much different it is that the outside air temp. in the climate control. Don't forget to remove the original foam rubber inlet adapter in the radiator header. You can help lower the incoming air temp. by fabricating a baffle between the engine and the actual air filter. Even an imperfect one will help. Did that 15 years ago using the stock inlet hose and cone K&N. Nothing wrong with the stock inlet hose by the way. The flowbench shows zero loss when the MAF is flowed with or without the hose. It's far bigger than the actual flow path inside the MAF.

Sorry about bringing up an old thread but I finally answered my original question, sort of. I have been working with TunerPro and a terrific guy there that helped me finally get a good recording interface for charting engine performance. Part of the process is to send a command to stop BCM communication after connecting the laptop to the ALDL. This does have the negative effect of turning off most of the IPC and the climate control goes into a default mode, but the information recorded appears to have very good synchronization. The TunerPro RT program is free and I made my own bare pin connector cable for laptop connection to the ALDL for <$15. Recording capacity limited only by the capacity of the computer, and I did so for over one hour on a drive home. The laptop I use is about (13) years old and is now the "garage computer", so nothing very powerful is needed. I keep one of the selected readouts on mph so I do have a speedometer of sorts. A datastream file is required from the website and I am not certain if the one they developed for me is available yet. PM if additional info. is desired. This program can also be used for modifying programming if you have the chip burning facilities, which I do not.

My intention is simply to present results that I find interesting and may be useful to others. There is truth in the fact that an exhaust system can be too large, or small, for a good balance between low end torque production and higher end performance. There are many articles out there with much research on the subject, David Vizard's research being one. I wanted to quantify a modification that many people have already done, not only on this forum, but the LeSabre and Bonneville guys too (probably other forums as well). One other item of some interest is catalytic converters. I removed mine many years ago but will be replaced and I tested the cheap 2.5" Walker universal converter. I have old data from the stock converter which I sacrificed some years ago. Again all tests are @ 28" w.c. except the last, which was @ 26.5" due to limitations of the small flow tube I have in place at the moment. The stock converter flowed 273 cfm, after gutting the cat., the flow rose to 323 cfm, but that is nowhere close to the 495 cfm flow through a 2.25" straight pipe of the same length. The 2.5" universal cat is somewhat shorter, and slightly larger inlet/outlet diameter, but it flows over 375 cfm, more than the gutted stock cat. I will rerun this last test with the larger flow tube used on the stock cat to see if there is a dramatic difference and report if there is. Edit: Ran the test on the Walker cat. again using the same flow tube as the original testing of the stock cat. The correct comparison number for the new cat. is 355cfm.

Yep, I ground one with a die grinder and carbide burr, but the hole saw works better. The exhaust is a low grade stainless steel so use plenty of cutting oil and slow speed. The one you have is pretty well centered but the unmodified one I have is offset almost all the way to one side. The outlet could probably be made a lot more efficient if the stub pipe before the flange was shaped more like a funnel, wider where it connects to the log part, without changing the length or location of the connection to the exhaust system, but a lot of work for unknown gain?

I finally got around to comparing a ported outlet exhaust manifold set to the stock system on the flowbench. All tests @ 28"wc. The test was done with the exhaust manifolds connected with the crossover and drawing air through the rear outlet. Each port was flowed individually and the O2 sensor was installed. The caveat is that the ported manifolds are also smoothed at each exhaust port which forms a more consistant bellmouth air inlet and the ported set I have is also ceramic coated inside and out. The cfm comparison is as follows: Stock-------Ported #1=178 #1=222 #2=203 #2=249 #3=169 #3=184 #4=152 #4=203 #5=165 #5=201 #6=169 #6=197 The largest percentage increase was #4 which dumps into the log of the manifold at almost a right angle and the ragged outlet hole in the stock manifold log has the hole shifted almost all the way toward #6 which apparently causes a lot of turbulence for #4. When the hole in the log is opened up to the outlet diameter the #4 outlet becomes visible through the outlet. Wether the engine needs this easier breathing or not is an open question.

The holes for the various EGR passages for the solenoids are quite a bit smaller than the base plate so alignment isn't critical. The round plate on the bottom of the solenoid is also larger than the passageway it controls so that shouldn't be a problem either unless something is defective. It is possible that the plunger could be sticky but is easy to check. EGR delivery is also dependant upon the gear the transmission is in, somewhat intertwined with the low rpm and lockup under 50 mph, where ignition strength is critical.

You should be able to connect a volt meter, or test light, to the green connector under the hood near the brake system. This connects directly to the fuel pump wiring to prime the system using 12vdc. It will also indicate if the fuel pump is getting power when this happens, but the symptoms sound like classis crank sensor failure. I believe I have heard of changing the sensor without removing the balancer, but unless it has be done recently, the sensor mount is probably stuck on a dowel pin or the screw clamp on the mount is a tight fit even with the adjuster screw loosened. I would remove the balancer.

Disconnecting injector shouldn't harm anything, you can manually turn them off via the onboard diagnostic overides. Possible the injector is stuck or plugged? It wouldn't make much difference even if getting the signal from the ECM. Do the plugs look substantially different in the affected cylinders? Can you hear a sharp click as the injector cycles? Even a large screwdriver touching the injector and held to the ear will help to see if they all sound the same.

I believe that is correct. Everything I have found says that the ratio is 1.6:1

I am pretty certain of this data, derived from installing an '88 and '90 cam in my spare engine and degreeing the cam. I am not certain, but I believe the '89 cam is the same as '90, since the lift and duration matches old data I have from the rebuilt '89 engine I have in the car now: 1988: Intake and exhaust lobe lift .271", Intake and exhaust duration 192-193 deg. @ .050" lift. Lobe separation 112.5 deg., 109 deg intake centerline. 1990: Lobe lift; intake .251", exhaust .255, Duration @ .050", intake 187deg, exhaust 189.5deg; Lobe separation 115.5, intake centerline 113 deg. These are both used cams but I ran the same numbers using #6 cylinder as the baseline (the other end of the cam), and all of the numbers were generally within 1 deg. of the same and lift within .002".

Do those have our style of electrical connector (EV1) or do they require an adapter? I have been looking for a photo of them but haven't found them yet. Are they the new style "skinny" injector and possibly white in color? I "thought" the stock injectors for the late model Series 1 L67 injectors were about 36#? I am looking for something affordable around 39# for E85 use, even used ones, that is why I inquired about the part number. Thanks for the help.

Do you happen to know the brand and part number for the 36# injectors? Pushed to 50psi would be just shy of 39#, about what I need to run E85.

The stock LN3 injectors are only about 19# per hour and are not large enough for the L67. Even if the fuel pressure on the L67 is higher, I don't think you will have enough fuel for high power runs. I would think your fuel trim (BLM and INT) should indicate higher than the target of 128. Daniel can probably give better info as to what to expect for program changes in the ECM. I am running 30# injectors on my turbo application and the EPROM had to be adjusted to bring the fuel trims back in line with the target values. I did try my initial running of the engine with the stock injectors, and it did operate reasonably well at around town speeds, but when pushed a little harder, the engine would lay down due to lack of fuel. I learned some things the hard way.

I know the maximum reading of 170 gm/sec is a frequency of 10.4kHz output from the MAF. I have a chart somewhere but I can't seem to lay my hands on it right now. Many years ago I requested air flow readings from stock Reatta's and the few I received were in the 125-130 gm/sec maximum, although I believe Padgett reported a bit higher at around 140. I posted a little while ago about the '88 camshaft which is a little more robust than the '89-'90 and I believe Padgetts test car at the time was an '88. I did not record the years for the others that responded. Is it possible the MAF from the L67 is bad? I will PM the MAF chart if I can find it. Edit: An approximate horsepower figure is 1.32hp per gram/second. It works as a point of reference for modifications.

Thank you Kevin. Your explanation makes this clearer and I had not seen the reference to the IPC in the manual. Input is much appreciated.

X2 on dealing with Ryan @ Sinister Performance. As to the MAF, did you record what sort of airflow the L67 was indicatiing? I was surmising that the LN3 MAF sensor was not reading consistantly due to the passageway not being a smooth tube for the air flow. I have only tested the LN3 and L27 style MAF sensor on my flowbench, which is the style on the right of my poor photo, and the frequency vs airflow range is exactly the same as the LN3. Your 1995 L67 may be different due to the higher arflow potential of the S/C engine? Isn't that the 225hp version? I would be very appreciative if you could let me know what the maximum airflow indication is when you get everything operating. Your ECM should limit out @ 170 gm/sec, and that engine should be very close, or over that reading. Thanks

I understand about the communication link and that is why I asked. I know bits and pieces but am not savvy enough to know the total picture. I know the cover contains a jumper to provide a redundant link but it must be removed to connect the scanner? Frankly, I don't want to change, or disconnect anything to record data, and it would be a method of last resort, it it would work at all. Perhaps I haven't happened upon the right scan tool to record data (this will be the 4th different tool)? The Auto X-Ray does work, but has limited recording and it causes the instrument panel to sort of pulse when connected to record, which gives me reason to question if all of the recorded cells actually line up with each other? Thanks for the input. P.S. I believe there is hardware/software available to remove the EPROM, plug in there, and both record and operate the car from a laptop? This is really the method of last, last resort, plus more expensive.