Mysterious Engine: A Pictoral of Andysdorm's low mile 1995 Riviera

We finally had a nice day today, 60-degrees, so I took a look under the hood for immediate signs of wear or problem areas.

Not a mechanic myself I took some pictures of my 'repairs' to show my engine's current condition and hopefully to get some good opinions on what might be the issue that is the bain of my Riviera.

Also this will help me located the areas that you suggest I look at.

The Whole Engine Top View


Brand New MAF and TPS(under/left with orange plug)


EGR system area of which was throwing a code last checked from Meinike


EGR Valve, not sure if it is obvious that it needs to be replaced or if this condition is normal for the age of the car.


Our repair of the EGR pipe leading to the Throttle Body. The dark brown is gasket maker compound.


Here is the only issue I saw that will eventually need to be repaired. It is a line below the airbox.



The airbox and filter is as clean as a whistle, new MAF and TPS sensors, secured what was thought to be a loose hose, and repaired the leak the shop informed me about comming from the circumfrance of the EGR tube at the point where it enters the Throttle Body.

Every time I find something to be replaced someone tells be that a malfunctioning unit would cause bad fuel mileage. So I repair it. Then the code still comes on, a new possibility, could effect fuel mileage, and on and on and on.

Having closely monitored my fuel guage I have observed 400miles per full tank. Newer e-Assist LaCrosse commercials boast 500 miles per full tank. I am pretty please with what I get for my non-eAssist engine on my 17 yr old car. Could be worse.

The job market in my field has been warming up and I may have an interview tomorrow. Still, I can no longer replace everything "just in case". So I am entertaining all suggestions on what to look at or replace but I may hold off if some suggestions require fixes costing $200 or more.(Still not guaranteing success)

Important piece of info missing from above: what problem(s) are you experiencing with the car?

looks like you need some valve cover gaskets 15 from GM many things can affect MPG i just try and keep things lubed up (add anti friction modifyers to the oil) keep proper air in the tires and a nice coat of wax. good belts bearing and keep the EGR clean filter clean. make sure no KR and soon to do full header wrap on stock exaust to help scavanging on the exaust side and keep under hood temps down ( the S/C heats up the intake charge too much as it is)

AA wrote:

Important piece of info missing from above: what problem(s) are you experiencing with the car?

Ah, yes.


Engine light goes out everytime the car is turned off. The light does not come on unitl driving the car for awhile.

In some instances there is no rhyme or reason for the light to come on; a slight turn in the road, sometimes at the same areas of my trip without being a noticeable cause, I seem to think it could be connected to a thermostat(light only comes on after 205-210degrees).

Now for the noticeable problems of which sometimes occurs when the light is off.

-after a long trip 55miles or more the car will feel like it is pulling or jittering slightly
-if the car sits idle for awhile it will rev a bit then sound like it's falling to the point of stalling but hasn't yet.
-happened last Summer but was fixed when replaced TPS, the Riv will rev to 2-2.5 in park, it has recently returned


After we had "fixed" the loose hose it started doing it's wierd revving and falling. I turned it off and the next morning I drove home without issue, no light no pulling or jitters. I even passed a few cars and gave it some gas just to test it out. It looked good. The morning after the light came back on.

This is why I call it a mysterious engine. It has it's good days.

2000ws6transam wrote:

looks like you need some valve cover gaskets 15 from GM

When my GF's dad was helping me with my car he poured some oil over the funnel and it got everywhere. It started to smoke. I got to thinking the revving and falling was caused by the air intake taking in some of that dirty smoke since I have thankfully not experienced it since.

He was making fun of me for having a funnel and he's the one that makes a mess. Seriously, sometimes I think I have more skills than he has and he's a nuclear engineer. You should see my GF though; she glows green.

One, fix that corroded wire - the corrosion you can see is a fraction of what's there. (pic 6)

Two, plug in the airbox sensor. If it is unplugged it will set a code. (also pic 6)

Three, check all of your vacuum harness for leaks. It looks funky in the pics. And if the rubber tees are hard you should replace them but be careful not to snap the hard plastic line. Some people have replaced the hard plastic vac harness with rubber hose and plastic tees, and that's an OK way to go & does not take much line or time. Why?? because leaks in that vac manifold will set a code, matter of fact that code will say your EGR is wack... so if the rubber tees are hard it's time to replace them. You can get them at full-line parts stores, in my area a NAPA or CarQuest.

Albertj

lowwer intake gaskets will make cars rev up and down the car tries to correct it thought adjusting the IAC and its like a dog chaseing its tale! i know it can be a pain but pull your plugs and check if they look all simmilar in color. maybe when its dark mist the engine with some water and see if you have any shorts in the wiring i know i use to have a loose wire behind my radio when i would turn a corner it would mess stuff up lol ( eventually i had a dash fire) um um you ever get the car scanned ? auto zone or someplace like that will usually do it for free so you can buy their parts to fix the problem lol

hummm 200 degree t stat going 210 + ... usually bad stat or water pump i seen bad water pumps cause all kinds of weird stuff start with the cheap parts first if you decide to check that route

when it comes down to it a engine needs 3 things: spark, air ,and fuel. but re-reading your stuff it sounds like some type of air leak weather it be an intake or vacume. your MPG sounds a little better then mine and checking my LTFT's they were perfect!!! anyway sometimes you can see a air leak on a plug by having a really light color ( white to light brown) as the engine cycles thought the combustions it picks up the lean condition on the O2 and adds fuel, but the other cyl's are running normal so they will get too much fuel causing a wierd idle missing exc. depending on how bad the leak even a fried piston. you have the Series I engine i dont know as much about i had a 97 GTP and now the 97 rivi .... I got this care because my ex had a 95 and i loved to drive it!!!!!!!!!! i rebuilt the s/c and replaced the plugs and elbows for coolant on the intake.

albertj wrote:

Two, plug in the airbox sensor. If it is unplugged it will set a code. (also pic 6)

I knew someone would catch that. I unhooked the plug to get into the air box just to double check that the clean filer I put in last summer is still good. That's when I noticed the corroded line. I reassembled and plugged everything back in after the pictures were taken.


I believe you've suggested looking into the vacuum harness for my situation before. As not to seem like a total noob I tried refferencing a pic online so I could check it myself. I didn't come up with any pics. What does the vacuum harness look like? Is it part of the system my GF's dad put the copper wire around?

I wouldn't mind replacing it, does it go by another name in the industry? I tried looking at parts stores too.

Oh nope, here it is.


I can buy universal for this replacement, right?

Yes, I see the copper wire wrapped around one of the vacuum fittings. Those vacuum rubber connectors get brittle and can cause endless headaches, similar to what you are describing. The nylon vacuum lines also get brittle and break. The rubber connectors are more likely to be causing lots of little vacuum leaks though.

2000ws6transam wrote:

lowwer intake gaskets will make cars rev up and down the car tries to correct it thought adjusting the IAC and its like a dog chaseing its tale! i know it can be a pain but pull your plugs and check if they look all simmilar in color. maybe when its dark mist the engine with some water and see if you have any shorts in the wiring i know i use to have a loose wire behind my radio when i would turn a corner it would mess stuff up lol ( eventually i had a dash fire) um um you ever get the car scanned ? auto zone or someplace like that will usually do it for free so you can buy their parts to fix the problem lol

I had my sparks and wires replaced recently, about 2 yrs ago. I know getting to the lower sparks can be a big job for a Riv's engine; at least on the 1995 Series 1. Hope that's not it.

I did have the car scanned at AutoZone and it didn't read since they were using an OBD2 reader and my Riv falls under the stupid 1994/95 OBD1.5 system that nobody uses. Meinikee(sp?) was really the only 'free' read service that I could get for the car. My mechanic could do it but that guy has had sooooo many chances to fix my car and it's always in within a month or two later. If the car breaks down he is really the closest shop to tow it to. My parents trust him; I don't, spent way too much money. I am really enjoying learning how to fix my own car and save $$$.

Meinikee said it was an EGR code, then shown me the area effected which was the leak of the EGR tube at the Throttle Body. But that's not the only source of this issue as we found out.

I'm in need of an oil change and their service is cheaper than buying the parts with a coupon I have so I'll have then read it again. They are kinda wierd about giving me the findings. They'll write the codes on a piece of paper but will not photocopy the paperwork for me.

2000ws6transam wrote:

hummm 200 degree t stat going 210 + ... usually bad stat or water pump i seen bad water pumps cause all kinds of weird stuff start with the cheap parts first if you decide to check that route

That's one thing my GF's dad pointed out. The car does not overheat but the guage always just goes over 200 degrees. He heard in the engine that the pulley on the water pump was making noise and saw it move a bit. This will be a spring project for him and I. He has replaced one for an 97 Old Cutlass(Henrietta) so it sould be very similar.

Both my old Riv and Miata had to have their radiators replaced so I am in tune with watching the temp guage. I figured just over where it should be was just a sign of age.

2000ws6transam wrote:

when it comes down to it a engine needs 3 things: spark, air ,and fuel. but re-reading your stuff it sounds like some type of air leak weather it be an intake or vacume. your MPG sounds a little better then mine and checking my LTFT's they were perfect!!! .

I hear a lot of people mentioning that it has to be an air leak. I hope this narrows down a repair list.


When I was comparing the e-Assist to the Riv's engine I really don't know how many gallons can fit in the tank of a newer Buick; I believe we have 20-gal tanks. At half tank I'm between 200-210 miles, assuming ran til empty would result in 400 or near that. 20mpg is not the greatest for me considering all my highway driving and old lady driving to prevent the light from even comming on. Driving the Riv as it's meant to be driven, like back in my high school days I could problably see in the teens for my current Riv's engine.

My 95 has many of the same issues.I dont have the patience anymore to chase em around.I'll live with what I have and when able,drop it off at my mech and pay the diagnostic fee.it sux but she runs and aside frome tantrums,she rides good.All those probs only happen when I come to a stop.highway wise she does real good.

I tried to use a propane enrichment test,nothing showed up. At that point I gave up.

robotennis61 wrote:

My 95 has many of the same issues.I dont have the patience anymore to chase em around.I'll live with what I have and when able,drop it off at my mech and pay the diagnostic fee.it sux but she runs and aside frome tantrums,she rides good.All those probs only happen when I come to a stop.highway wise she does real good.

I wish the Actron scan product that worked for out Rivs were more avaiable in stores. I'd hate to have to buy one online and find out it didn't work like the 2 I have now.

My issues are only a concern for me at a stop as well. I tend to give a half car's length for when I know I'm stopping at a long light. It allows me to give it a little gas when it starts to go nuts. Sorry for all those folks in front of me that think I'm being impatient and trying to get closer on their tails.

Andysdorm wrote:

albertj wrote:

Two, plug in the airbox sensor. If it is unplugged it will set a code. (also pic 6)

I knew someone would catch that. I unhooked the plug to get into the air box just to double check that the clean filer I put in last summer is still good. That's when I noticed the corroded line. I reassembled and plugged everything back in after the pictures were taken.


I believe you've suggested looking into the vacuum harness for my situation before. As not to seem like a total noob I tried refferencing a pic online so I could check it myself. I didn't come up with any pics. What does the vacuum harness look like? Is it part of the system my GF's dad put the copper wire around?

I wouldn't mind replacing it, does it go by another name in the industry? I tried looking at parts stores too.

The GM dealers call it a vacuum harness. It was pretty funny when I replaced mine. I had to look up the part on a fiche and give it to the counterman, he could not find it. I posted a note about this a couple weeks ago. The old num is GM #24507329 and I think it's the same for all the SC Rivieras; let them find you a replacement (they still make/have them).

You can replace it without the GM parts with a packet of tees and caps, and some small-gauge vac hose. Info about that is in the thread with my old post. I think it is here:

https://rivperformance.editboard.com/t8957-p0104-egr-low-flow-code

The thing about the Riv EGR is the flow is never really measured. The low flow code is their "proxy" for a vac leak at the MAP, the SC vac dump valve, et cetera.

Really, a few feet of the teeny gauge rubber vac tubing and a couple tees should do it although not as elegant as factory.

Albertj

Albert,
I don't think the 95 has the same vacuum harness.
-Derek

If you're driving more than 80% highway driving without any traffic then I would assume your mpg should be a little more. Keep in mind, these cars suck gas in city driving. If I'm only doing city, my mpg plummet from 27 to about 17. Momentum and gearing are this car's friend. lol

deekster_caddy wrote:

Albert,
I don't think the 95 has the same vacuum harness.
-Derek

I think you may be right *but* if he gives the number to the counter person he will have the proper nomenclature, and the counterperson will have a good idea of where to look on the corresponding diagrams on line or on DVD. The new number was 24508742 by the way, for the '96 and later. Might want to try that one - to get hte location and nomenclature - if the other number does not help.

Tell the counter person they are looking for the "vacuum harness" or "Vacuum Manifold" - I think it is listed as vac manifold in the Trademotion catalog and vac harness on GM's online parts system.

When the counterperson puts the old number in he'll find it's been superseded, and the new number *might* show discontinued but if the counterperson looks in the GM dealer database there should be many out there. At least he will see the proper nomenclature and find the thing if it is available. Looking at the tag, mine came from GM SPO in Martinsburg, WV. "HARNESS SPCHG B" catalog group 03.374.

Albertj

Part 6,7,8, and 9 total to about $31.43. I can easily do that.

good luck hope that fixes the problem. keep us updated

Andysdorm wrote:

Part 6,7,8, and 9 total to about $31.43. I can easily do that.

bingo.

I suspect that's part of the problem. don't wig out if it does not fix it 100% - what you're battling is a bunch of one time maintenance items you only see on hi mileage vehicles.

Part #6 has been discontinued. Seriously?!

I was able to order all of the other parts. Watch it been the part that causing the issue.

Now would you suppose I could pull off that missing piece from a universal replacement part?