Car previously dyno tuned on bad MAF

Hi all, sorry if there's forum etiquette I'm missing here (this is my first post) but I have a question.

 

My 05 LGT 5MT wagon has had this stumbling feeling between 2-3K RPM for awhile now and I've replaced numerous parts (upstream O2, MAF, PCV valve, plugs, clutch) and all have seemed to help this stutter a bit, but never rid it completely. (In case anybody is concerned, I am going to compression test the engine on Tuesday (7/23/19) as the car burns about 1 QT of oil every 1000-1250 miles or so, despite the new PCV valve.) Car has 206K miles with the original engine.

 

Car was previously dyno tuned by Jared at PDXTuning with a bad MAF sensor (unknown at the time). The car didn't have a steady CEL related to the sensor but would sometimes leave a code for overboosting. The car would also occasionally die at idle or with the clutch pushed in. All of these symptoms have been remedied with a new MAF sensor and PCV valve, however the car still stumbles and seems to get slightly worse fuel economy than it should get considering all I do is freeway driving with heavy use of cruise control (21 MPG).

 

My question is whether or not a car dyno tuned with a bad MAF sensor would result in a wacked out tune when replaced with a good MAF sensor? The car had a much smoother idle and made noticeably more power under all loads with the new MAF, but the fuel delivery has seemed pretty weird since.

I'd recommend a new dyno tune to get the engine optimal.

Agree, may be it just needs a street tune, but tell the Tuner and ask him what he recommends.

 

A little more money now may save a lot more money later...

Strongly suggest calling Surgeline in Tigard to have Chris put it back on the dyno to re-tune. That said, with 206k on the motor, you’re slated for a new one soon if your trying to push power thru it

Agree, may be it just needs a street tune, but tell the Tuner and ask him what he recommends.

 

A little more money now may save a lot more money later...

 

Strongly suggest calling Surgeline in Tigard to have Chris put it back on the dyno to re-tune. That said, with 206k on the motor, you’re slated for a new one soon if your trying to push power thru it

 

I'd recommend a new dyno tune to get the engine optimal.

 

I'm going to PRE Racing on August 1st for a dyno tune since my car is catless and I want the downpipe cat on there for good and have emissions coming up. Cobb Surgeline was very friendly when I talked to them on the phone but I scheduled this tune over a month ago and had some financial uncertainty at the time and didn't want to spend the money on a Cobb AP. I'll post back if the comp test comes back with some issues. The weather hit 90 degrees F today and the car ran super smooth. Car is just hellbent on being a confusing mess with no CELs

 

No plans to increase power. The 280 WHP it was pushing before clearly is too much for this motor with it's age and mileage. Planning on dialing it back closer to stock.

 

Thanks for the replies y'all, I appreciate it.

Edited July 22, 2019 by Pleides

i'd inspect everything... including the turbo. Is that the original turbo?

i'd inspect everything... including the turbo. Is that the original turbo?

 

Turbo has about 25K on it and no worrisome shaft play. No leaks.

For sure it would be an issue. That would have thrown the MAF scaling off and now your afr would not be right.

I had a dyno done with a bad O2 sensor on my 08 gt, should I be concerned?

The shop running the Dyno would likely use their own O2 wideband sensor for the tune, so a bad O2 sensor in your exhaust might not have been involved in the tuning process. You can probably just ring the place to confirm.

Well guys, shit just really quickly hit the fan, and I'm not sure what to say. Could use some recourse in a difficult situation. Things should hopefully be resolved within the next week. I may have to sell the car cuz I cannot afford a motor rebuild right now.

 

I took the car to PREracing in NE Portland. They installed my OEM downpipe and new downstream O2 without fuss like I asked. They also were gonna do a dyno tune on my car. Eric, who seemed very knowledgeable, ends up taking a few hours to do his thing and I notice that my car cannot be heard from inside PRE's shop (meaning he's not doing pull after pull on the dyno). After a few hours he comes back and him and the service/sales guy are going over what's wrong with my car. They end up telling me I've got 60 PSI on cylinder 1, 100 on cylinder 3, and around 140 on the other two cylinders. Eric put a very conservative tune on the car and told me whoever did the tune before didn't even adjust the factory timing on the tune. We all noted that it was really weird that the car failed a comp test on what are typically the two most reliable cylinders. Ringland failure was suspect. Car burns about a quart every 1K-1250 miles. Eric raised the idle a bit to compensate for where he said the car would misfire. I should point out that I never asked for a compression test, in case anybody is wondering.

 

I started calling around for motor rebuilds and called my trusted mechanic. My mechanic did a pre-dyno inspection and oil change last week and noted the car seemed fine, drove with lots of pep, and generally worked as it should bar some iffy tuning issues (to be expected given that the car was tuned on a bad MAF). My mechanic Ben, who does most of the work on my car, decided to do a comp test on the cylinder that PRE found to have 60 PSI. I held the gauge while he cranked and the car ended up having 140 PSI on that cylinder - a VERY different result than PRE. Unfortunately, due to their lack of staffing, we had to wrap the car up and schedule next week for a full comp and leakdown test.

 

Also noted - I was under the car while the plugs and coil packs were out. PRE noted on my service sheet that I had a leaky driver's axle boot. I did not notice anything leaking from under the car bar a boot on the steering rack. Axle boots seemed fine all around.

 

I'm more than a little skeptical of PRE now. Has anybody had bad experiences with them? It's all leaving a bad taste in my mouth.

Edited August 2, 2019 by Pleides

See post #4 Sorry to hear about your troubles, I'd suggest following my advice. I still think your on borrowed time with 206k on that motor. Edited August 2, 2019 by shralp

https://www.cryotuneperformance.com/

 

Like I have said for many years here there are only two Tuners I trust, Dave is one of them.

 

Contact him for help. If you have a Cobb AP or are able to data log, I'm sure that may be something help need.

 

I would have your guy Ben do a complete compression test.

 

These cars are also know for PS rack leaks, had mine replaced back in June 2012.

A second (or third) opinion is never a bad thing. Shralp had a good suggestion.

 

Also a compression test is a normal part of most pre-dyno inspections.

 

I had a cylinder fail compression test during pre-dyno inspection as well... awful feeling.

valves maybe? when compression is wonky like that I would go one step further and do a leak down. I'd want to be sure before you start pointing fingers!

Valve clearance issues can give a hit and miss compression test indication. But it can also be caused by sloppy attachment of the gauge or even a dirt in the gauge valves.

HMS is another reputable shop as well. They just moved to appointment only because of how busy they are so you'll have to email to explain and schedule.

See post #4 Sorry to hear about your troubles, I'd suggest following my advice. I still think your on borrowed time with 206k on that motor.

Thanks, I'll definitely be giving them a call. I know they're reputable. Sadly they require a Cobb AP for their tuning which I don't have.

 

https://www.cryotuneperformance.com/

 

Like I have said for many years here there are only two Tuners I trust, Dave is one of them.

 

Contact him for help. If you have a Cobb AP or are able to data log, I'm sure that may be something help need.

 

I would have your guy Ben do a complete compression test.

 

These cars are also know for PS rack leaks, had mine replaced back in June 2012.

I'll have Ben do the test Wednesday next week and I'll know by then what's going on (hopefully). I do not have an AccessPort or any method of data logging. PRE made shop notes of things they claimed my car needed but somehow, despite seeing a driver's front axle seal leak (that doesn't appear to be there from my viewing of it), they didn't notice the PS rack leak.. kinda weird. Do you replace the whole rack or can you just replace the boot?

 

A second (or third) opinion is never a bad thing. Shralp had a good suggestion.

 

Also a compression test is a normal part of most pre-dyno inspections.

 

I had a cylinder fail compression test during pre-dyno inspection as well... awful feeling.

Eric only did the comp test because he said my car had a cylinder 1 misfire as the car settled back to idle after a clean WOT pull on the dyno. The only pre-dyno stuff they did AFAIK was the vacuum leak test.

valves maybe? when compression is wonky like that I would go one step further and do a leak down. I'd want to be sure before you start pointing fingers!

I'll have to see how this goes. 80 PSI difference though? I know difference gauges can show different numbers but that's hugely different. Car has never had a valve adjustment though.... so that's a potential point of failure.

Valve clearance issues can give a hit and miss compression test indication. But it can also be caused by sloppy attachment of the gauge or even a dirt in the gauge valves.

This could be it. As stated above, car has never had a valve adjustment and I believe had the stock tune for about 180K miles.

HMS is another reputable shop as well. They just moved to appointment only because of how busy they are so you'll have to email to explain and schedule.

I would LOVE to use Horizontal since they're a 15-minute walk from where I work, which is really convenient. I'll have to see how things go on Wednesday. To be frank, although I love the wagon, if the car needs serious engine work then I'll have to sell it as it's just been a huge cash suck for me. Unless y'all think I can get 10K miles more outta the engine lol

Yes, had my trusted mechanic replace it (PS rack) when he could get one of the trusted brands from his supplier, that was back in 2012.

these are the reasons i have lost faith in auto shops and have gone the diy route... i'd rather waste money and learn than pay money and stay ignorant, it usually works in your favor financial wise.... not saying there aren't honest shops, it's just the dishonest or incompetent ones ruin it for everyone else....

 

you can own both a compression and leak down kit for under 100 bucks... vs paying someone to do it for you, and you can do it as many times as you want in the long run...

 

"You can take a good look at a T-bone by sticking your head up a bull's ass, but wouldn't you rather take the butcher's word for it?"

 

-Tommy Boy

 

this is not that case.... i would rather stick my head up the bulls ass!

 

knowledge is power, otherwise your at the mercy of those with it...

Edited August 2, 2019 by Tehnation

these are the reasons i have lost faith in auto shops and have gone the diy route... i'd rather waste money and learn than pay money and stay ignorant, it usually works in your favor financial wise.... not saying there aren't honest shops, it's just the dishonest or incompetent ones ruin it for everyone else....

 

you can own both a compression and leak down kit for under 100 bucks... vs paying someone to do it for you, and you can do it as many times as you want in the long run...

 

"You can take a good look at a T-bone by sticking your head up a bull's ass, but wouldn't you rather take the butcher's word for it?"

 

-Tommy Boy

 

this is not that case.... i would rather stick my head up the bulls ass!

 

knowledge is power, otherwise your at the mercy of those with it...

 

I can count on one hand the number of shops I can trust in the Portland area that I've worked with. Raleigh Hills (my mechanic) and GER-BROCK in North Portland - actually an easier shop to work with but they don't do huge engine work and they're far from me. But I do trust Ben at Raleigh Hills, he literally did the comp test with me and that shop has been doing work for my family since before I was born. I also have tried to remove the spark plugs from this car myself (what you'd obviously need to do for a comp and leakdown test) and have yet to figure out how to get the fourth one out without lifting the car up. I can typically access a lift at work (new/used dealership) but only on the weekends when our mechanics don't have their tools out since the service dpt. is closed weekends. I tend to do a decent amount of work on the car myself but this is something that I'll leave to people who have removed the plugs thousands of times on these. Anyways, excuses and long explanations aside...

 

We'll know by next week. Either there's enough life in the engine to drive it until it blows and I can do a full engine rebuild with more money saved up, or we sell the car for not much.

 

For those with an AP, has it paid for itself? I've kind of avoided Cobb Surgeline literally only because I'd need an AP as kind of a gateway for a lot of their work and it's nearly 700 bucks. I don't really want to pay $700 for a glorified key and code scanner.

To do #4 plug, you fit in socket, extension, then thin wrench.

Break it lose, 1-2 turns, then remove the wrench.

Loosen the rest of the way by fingers.

Separate the extension from the socket and remove separately.

It’s not easy, but after 6-8 times I’m used to it.

ap i would imagine is easier to manage than lugging around a laptop all the time, you need to charge it etc. It also has off the shelf tunes. its just a simpler tool to use. they really have a lot of functions, gauges, logging, tuning, even has a shift light... and i use opensource. you go opensource you have to pay for a tactrix cable which is like 200 bucks, you will need a laptop as well... if your comparing things evenly the ap is probably cheaper and easier, than buying a laptop and tactrix... Edited August 3, 2019 by Tehnation

Alright, here's how things have gone:

 

I did a compression test with my mechanic Ben. Below are the results:

 

140, 125, 145, 125 - cold tested

 

Cylinders 2 and 4 had suspected worn piston rings.

 

PRE's were:

 

60, 130, 100, 150

 

So I don't think I'll be back at PRE. Scheduled a dyno with Surgeline for September. Kinda bummed. Really liked Austin at PRE. Think they just saw a young guy with a fast car and assumed I had abused the thing and would pony up for a new motor... I dunno. Joke's on them - I drive like an old lady lol

Also worth to double-check the cam timing for 2 and 4 so you don't waste time on the wrong problem. Slightly off timing could lead to compression error.