2seater

The manifold should be solid aluminum and it is virtually impossible to burn it. The only problem I have ever seen with these is the coolant passage area may erode and cause a water leak, usually at the drivers rear of the engine. It may be possible to displace a gasket, blow off a vacuum line (look closely at the PCV area, the grommets have been know to disintegrate). Even the MAF sensor is protected pretty well from backfire problems. If this engine has the plastic snakes manifold, the early model was prone to problems. The diagnosis sounds suspect to me. None of the sensors are operational at startup, only the crank sensor and the ICM below the coil pack are used for starting, and they must generate a signal to the ECM to pulse the injectors once for fuel to start the engine. Even the cam sensor is not required to start and run the engine. A serious vacuum leak, low fuel pressure, a sticking/burned valve, bad crank sensor, or valve timing that is off may cause a backfire. Are the coolant, air temperature and TPS sensors reading correctly? They can have an effect on the reference to the ECM for startup (engine warm or cold?)or if the TPS is reading full throttle it will turn off the fuel to the injectors.

I have seen an installation done somewhere (can't remember where exactly) but it was driven by a jackshaft. There is little room on the front of the engine so the shaft transferred power across the front of the engine above the front valve cover and the compressor was located about where the air box is, very similar to my turbo installation. The engine itself does not care about boost, all engines run on atmospheric pressure, or actually the differential pressure between the ambiant and the lower pressure inside the manifold and cylinders. Boost simply makes that difference larger for better cylinder filling. The only pressure sensing our engines are capable of is the fuel pressure regulator and that will respond to positive pressure just as well as vacuum. The fuel pressure will rise in a 1:1 ratio in response to boost to keep the differential pressure between the injector fuel and the pressure in the manifold to keep the fuel delivery constant. The stock compression ratio is just fine for a few pounds of boost and there is no documented evidence the bottom end of the N/A engines is any different than the supercharged ones. On the later models the only difference that can be found is the piston pins are full floating vs pressed on the N/A engines. My experience has been the stock system will tolerate and adjust for 4#-5# of boost although slightly larger injectors will be needed to be safe. This will take the engine air flow up to the air flow measuring limit of the MAF. While the engine will run fine, there are other tweaks that will be helpful and the increased power must be used with discretion. The horsepower increase will be very noticeable but the torque increase will be larger and dead stop full power acceleration will be hard on the transaxle, probably the weakest link. This can be done, but it will require patience and a fair amount of experimenting.

Water has a higher capacity for absorbing heat, but it also boils and freezes more easily. The antifreeze simply changes the freeze and boil point, but it does displace some of the water, lowering the heat carrying capacity somewhat. Achieving the proper balance may take some experimenting. Generally a 50-50 will give plenty of boil protection and more is only needed in extremely cold climates to lower the freeze/slush point. There are other advantages to antifreeze, it provides corrosion protection, lubricates the water pump and tends to lessen the tendency for the water to boil where it is in contact with hot engine parts, like in the cylinder head. The pressure in the system helps keep the bubbles in the coolant smaller for better contact with where the heat exchange occurs as well, plus it also raises the boiling point. There are other coolants out there, propylene glycol for one, that can be run in the pure form, but the goal is usually to raise the engine operating temperature without causing vapor bubbles in the coolant which reduces heat flow. Essentially they are trying to improve engine efficiency using higher temperatures, without the risk of localized hot spots.

That does not sound unusual. If the brakes work normally otherwise, and no lights, they can gradually drop towards the floor with constant hard pressure. My parking brake takes 3.5-4 pumps to lock up tight although one never gets as tight as the other. It's a good idea to exersize the e-brake occasionally to keep the rear brakes adjusted up. If the warning lights come on after a couple of quick applications it sounds like the accumulator is on the way out.

I don't believe the non-tow advisory is as much drivetrain related as it is suspension and wheelbase. The same drivetrain was used in full sized cars as well (Bonnevilles, LeSabre's etc..), and even though the Riviera is a kind of in between size, it does have a longer wheelbase. The weight capacity of the Reatta is quite low, about 500#, and the suspension is soft to get a decent ride with a short wheelbase. The drivetrain is stout enough, and an additional trans. cooler would be a good idea, but my suspicion is stability may be the issue.

The rear bank gets very little air flow to cool the area. The radiant heat can build up to a greater extent than the front. Personally I installed Accel's Extreme 9000 wires with silver boots and even with the heat from turbocharging and a rear manifold closer to the plugs, I have no problem without shields. I used wires with 135* Ford style boots which stand the plug wires almost straight up mimimizing the area where radiant heat is the most intense.

Is Ethylene Glycol made from petroleum? Even if it is it sounds like someone is taking advantage. Maybe a big lawsuit out there somewhere?

How do you remember all that good stuff?

Actually, the manual recommends 5w-30 only if the temperature drops below zero F. Above zero, 10w-30 can be used and if always above 60 deg.F, straight 30 is acceptable. I haven't found straight 30 in pure synthetic yet. Our engine uses tight clearances on the bearings and "fatter" oil isn't needed unless oil pressure is a problem. That crank driven oil pump spins twice as fast as more conventional types, and usually oil pressure is not a problem. My turbo does steal some of my oil pressure so I have gone to 5w-40 Mobil 1. I have searched the manual and I do not find any recommendation of synthetic vs conventional oil as long as it meets the minimum specs, and everything commonly available today is light years beyond where they were 15 years ago. All oils are pretty good.

I think the turbo Trofeo guy is still around but I think it has been retired for the time being. Mine has been turbocharged for two years (I don't know what happened to my signature photo?), and am gradually getting it sorted out. GMTuners has modified my old Fastchips and I am gradually getting the knock retard under control. Down to 6 degrees retard at full boost without alcohol injection and 3 degrees with it turned on at 5 psi. More tweaking needed and even larger injectors than I have now. Apparently it produces more hp. than my original target of 250.

I do believe it is a fwd car but the transaxle is arranged differently. They used 403 Olds motors in those cars too, sorta like the original Toronados. Part of the turbo setup I used came from a '78 carb'd and turbo'd Riviera. Any turbocharging you are going to try will involve fabrication of many parts but it may yield parts you could use. Supposedly there are now kits out there, lots of dollars, that would be closer to what you want, but even they are not designed as a direct bolt in for our cars. There are a couple of kits available for the S/C cars, that remove the guts of the supercharger and blow a turbo into the housing. More performance potential than the supercharger.

A 1990 should not have the "E" transaxle. It should be the plain old 4T60. The electronic trans. was introduced in the Reatta in 1991, but sometimes there are exceptions if it was a late production. Does anyone know if the vacuum modulator disappeared when they went electronic? If so it would be easy to tell.

It should be a ten minute job if it sits right on top like all that I have seen. Disconnect battery ground wire. Use an 18mm (I think)socket or wrench on the nut in the center of the tensioner wheel to release tension and slip the belt off the alternator. Disconnect the plug on the top and the hot wire from the rear of the alternator. Remove the two bolts at the front and rear of the alternator and it should lift straight up. Assembly is the reverse, and the only thing to watch for is all of the grooves on the belt line up with all of the pulleys. Look carefully at all of them with a light, they won't self align on start up. The tensioner will adjust the belt tension automatically. While the belt is loose, feel the tensioner pulley to see that it doesn't wobble and rotates smoothly.

Same problem in Wisconsin. No kits are available to the public and they won't ship here if bought elsewhere.

Aside from the claims, which sound typically to good to be true, it struck me as odd it mentioned the Reatta's specifically, which is a much smaller crowd than the other 3800 powered cars out there. Not to say the stock systems cannot be improved, but a compromise in some other area generally is the result. While GM could have improved the product earlier, as the Series II shows they are capable, they did a pretty good job getting the system you have now balanced pretty well. As others have mentioned, money would be better spent on standard "improvements".

That does sound odd. The book for a '90 shows a (14) cavity connector with (13) being used. I checked it against my car and it looks just like the book? Something like (6) are used for the cam and crank sensors, a couple more for the timing signals from the ECM, others are power and ground, a signal to the injectors etc. Maybe some of the connections were displaced from the ICM to a separate connector, such as some of the common connections used for the cam and crank sensors? It would be interesting to see how they are different if the ECM operates the same as all other'90's.

Uh, yeah, 3000 rpm should be over the posted limit about anywhere (except maybe the Autobahn). 2500 is about 90mph on my '90. The '91's get generally poorer highway fuel economy, but I would probably sacrifice a couple of mpg to get the better acceleration, although the turbo pretty much took care of that.

Thanks for posting the solution. The odd thing about the ECM failures, and they do crop up from time to time, is it seems more age related rather than mileage.

It seems like it is likely more hype than a help. The basic engine internals are the same (a little longer connecting rod possibly) and for all the improvements, larger intake and exhaust, raised rpm level, a slighlty different operating system for the EGR, I would be disappointed in only a 5hp increase and 5% more torque, especially higher in the rev range. Generally longer intake runners will help the low rpm torque near the rpm they are tuned for, maybe in response to raising the torque peak rpm? The short runners of the older manifold design would tend to favor high rpm power, but the cam is so dead above 4500 rpm it doesn't make much sense? The tuned port style manifolds were available earlier, I have found aluminum versions on '89 Oldsmobiles in the boneyards. I agree with Padgett 100% that the biggest reason they are a little faster is the lower gearing, and it is a fair bit lower.

Did you check the actual fuel pressure? Forty something psi would be normal at the fuel rail after the pump primes. If the car was stored for an extended period it may be possible the filter needs to be changed, maybe the fuel has broken down and you actually have two distict problems? The two second prime from the fuel pump is normal when the key is turned on. If the operation of the fuel pump is suspect, you could just use the fuel pump priming wire under the hood. It has a green connector hanging loose on the drivers side of the engine bay. Applying 12 volts should cause the pump to run.

Welcome I hope you like it here and it's always good to have another enthusiast.

If you never get into boost from the turbo it will probably run happily on regular 87 octane, but if you use the engine anywhere near it's potential, premium will be required. At the least you will get spark retard from engine knock or at worst blown head gaskets or broken pistons from detonation.

How would you know that Riv's must have come with lower speed rated tires, maybe S or T?

You need to have the engine running and up to temperature to get good readings from most of the sensors. The O2 could be at fault or, a vacuum leak may cause the mixture to go way to the rich side. If all of the visible hoses are okay, run you hand over them and if you get a black stain on your fingers or a rag, (not just dirt)the hose should be replaced as it is likely getting porous. There is a hose to the instrument panel between the engine and firewall and is easy to miss. One other place is the PCV valve grommets in the intake manifold. Due to the location it is not readily visible and it gets good and hot in that location also.

Maybe, but I doubt it. I suspect it may have been oil related though. The whole reason for the change was a leak in the evaporator that coated the surface with oil and stuck on junk so air flow was seriously reduced. The a/c tech convinced him to changeover since the whole system had to be purged and taken apart, and that does make sense. The compressor may have died even if he stayed with R12. I do suspect some of the cases where compressor failure followed a changeover was the system had been running for some time in a less than perfect state, and it was only a matter of time. Not too many people take a system that is operating properly and deliberately spend money to change to something it wasn't designed for.