Golf IV / Jetta IV :: Car Runs Fine But Won't Boost Over Wg Pressure
Feb 11, 2015
I just got done with a complete engine rebuild on my 02 1.8t jetta, had everything hooked back up and went to start it for the first time and it wouldn't. I went back looking for loose connections, nothing. Worked and banged my head for a day or two, I had fuel and spark but couldn't get it to fire. Finally I "choked" the intake to see if it was getting too much air and it fired right up. I unplugged my map sensor giggles and it starts up perfectly. I then hooked everything back up and what do you know it starts up and runs fine, but if I plug the sensor back in it kills the motor after about 10 seconds of running and won't start until I unplug the map again.
Car runs and drives but wont boost over wg pressure but that's probably because sensor itself is unplugged. I just wanna know what could cause it besides the sensor itself being bad. I ordered a new one waiting for it to get here (hoping it fixes the problem).. And I'm talking map (manifold absolute pressure) not maf (mass air flow), just in case people are confused.
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I bought my GTI used and don't know what software its running but I have some questions about the boost pressure. When I'm in Idle the car will only boost to about 7-10psi when i rev the engine in neutral, But when I'm driving it will boost all the way to about 17-20psi if I really stomp it, 15psi if I'm just giving it a bit of "go". The car takes off and goes really quick, seems like it has a lot of power so I doubt there's a boost leak but I'm wondering does the car boost differently in Idle because it knows its not moving?
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my car into VAG COM and since then it hasn't boosted past 4 lbs. it has Revo stg 2, K04, aftermarket side mount, full exhaust and a couple other bolt ons. Before the car was spiking at around 23/24 lbs. after pressure testing the system I found that the turbo inlet pipe was lose, so I tightened it. Still no change. I tried holding the battery terminals together for 10 minutes to reset the ecu and I also tried clearing the codes through a handheld code reader. No codes even come up anyways for this. The car is a 1.8T.
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So I was waiting in line at a drive through, because Fast Food is the breakfast of champions. And suddenly my Oil Light started blinking. It beeped, then blinked. It didn't stay on solid.
So I figured I was suddenly low on oil. I then noticed my engine temp was pegged to the max. So I abandoned my Egg McMuffin (Not an easy choice by the way) and I pulled out of line into a parking spot and shut down my engine.
I gave it a few moments to cool down and checked the oil level. In the past my oil light has come on if I was low on oil and a 1/2 quart or so was all I needed. But after 20 minutes of cooling down, I checked the oil level and it was fine. Not even close to low.
I made some calls, talked to some people, ate a McMuffin and checked the level again. It was still good. So I restarted the car now that it was totally cooled down. It warmed up fine, right to normal temp, no overheating, no oil light and all seemed well. So I drove it home (About 12 miles) without issue.
Also, Prior to this issue (within a couple months) I switched to Synthetic Blend. And it may just be a coincidence, but my AC also failed about 3 days ago.
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So my 2001 1.8t Golf is having some issues holding boost. I have a Gonzo stage 2 tune, CTS FMIC, Forge 008 Diverter, Silicone inlet and MagnaFlow Exhaust. I've also done the whole Evap, SAI delete and installed a catch can.
Starting in 2nd or 3rd at WOT the car spikes up to 18psi and then progressively loses boost throughout the rev range. Close to redline the boost drops to 5 psi or so. It seems to be dependent on the revs. In fifth gear the car holds 18 psi much longer as the revs don't increase as fast.
There are no CELs. I've done multiple leak tests starting at the air box and plugging the pcv/catch can system as well as at the compressor side of the turbo. None of the tests revealed a leak anywhere in the intake system. However, when I stuck my ear very close to the valve cover I could hear what sounded like a very small air leak coming from inside the valve cover. I took a look at the wastegate actuator and it seemed fine, no play in the rod, no loose bolts and to move it just requires enough force to compress the spring and it returned to its original position.
My thoughts are that it could be a fueling issue or turbo in the process of dying maybe.
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Just noticed today that I have a slight drop in boost. Normal boost is 1.5 bar but today it is running slightly lower boost and does not have the same pull through all the gears.
2001 mk4 1.9 tdi golf
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I just recently notice a whistling noise when I hit boost. I'm not sure but it sounds like it is coming from my gauge. I'm not losing boost pressure. I do have a glow shift gauge. The most recent install was the TIP which I clamped on to the turbo but I'm wondering if it isn't on tight enough.
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I was riding along today everything running fine then I came to a stop sign and when I pulled off my car wouldn't run 10 psi of boost it was only running 5 psi so I when to a buddys checked everything over and all my piping looked fine so I went up the road and everything was fine so when I started going home it did the same thing pulled of shut the car off pulled off and it was fine again.
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I think my stock DV is going bad, my car makes a weird noise under boost?
1. Only happens when first starting the car after it has been sitting for an hour or a few. (not overnight)
2. Does NOT happen when first start in morning.
3. Goes away after like 5 minutes every time and the normal WHIIISHH sound comes back like it should when I step on the gas.
4. It does not make the sound at idle.
This recording I made was of my car being revved up after it sat for one hour.
[URL] ...
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2002 Jetta GLS 1.8T (engine stock except diverter valve) 171k miles
It's done this a couple times now. Both while raining out/high humidity. Prior to this, I could hear the pump "growling". Sounded like maybe starting to go. You could hear it prime when opening the door or turning the key forward but would stay sounding like that even when the car was started. Without the radio, you can hear the pump running.
1st time- The car will crank without issue but never start. I let it sit a few minutes, turned key, heard it prime,tried again, started right up like there wasn't an issue and I couldn't hear the pump this time while the car was running.
2nd time-The car will crank without issue but never start. I let it sit for an hour, opened door (couldn't hear prime), checked fuse 28 (good). Figured wth, let's try anyways. Turned key, couldn't hear prime, started right up. WTF. cold idle normal (1000-1200rpm), light revs to 3000 ish normal. Turned off car, let sit for a minute. Turned key, heard prime, car started without issue and I couldn't hear the pump again while the car was running.
My dad is thinking to replace the pump right away. Is there anything else to try? The relay is working... at least sorta. With the somewhat intermittent issue, where to start? Either way, relay or pump, I will be replacing fuel filter.
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My 03 GTI 1.8 is having start issues. It cranks up fine, but it sputters to a start. It doesn't idle high and fall down to the 850 mark like normal, it just lugs itself into low idle. I have to then throttle it until it stops sputtering and I have a smooth rev. Then after that, the car runs fine. I can stop it and start it up again fine when it's warmed up. I have checked multiple things already.
-The Ignition coils are in excellent condition
-Spark plugs are normal, but not exactly perfect
-Fuel pump works fine
-Battery was tested and is clean and good
-Throttle Body is clean (at least to the eye, Im cleaning it next)
-Oil was changed when I changed the sensor along with filter.
I should mention I changed the crankshaft position sensor a month ago. The block at least from under the car is filthy, but I don't know if that affects anything.
I had a check engine light, so I got its codes read (I'm out rn, but when I get home I can show you) and decided to just take it to a shop. When I took it, the light went away, decided to start as normal, and the shop just charged a huge fee for the diagnostic and nothing was fixed. I really need to know what to do with this, I daily it every day and its starting to bother me a lot now.
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Replaced my coil packs/sparks, and just got around to changing my N75 valve today. The rough idle issue is gone but now when I go WOT it boosts but goes from 15psi-12-13-12-14-12...etc. I've checked and there are no boost leaks. I do have a CEL saying I need a new bank 1 sensor 1 Oxygen sensor. If it is that, why did this problem arise as soon as I changed the N75 valve and wasn't present earlier?
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I was having an issue with my car not going into boost so I plugged my code reader in and it had 2 codes 1 was p1200 n249 malfunction and the other was diverter valve malfunction so I did the quick easy one and got a new factory diverter valve but it still doesn't go into boost and still reads p1200 n249 what do I need to replace or should I do the n249 bypass it's a bone stock jetta 5 speed.
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I got a Mk7 in October and my Mk4 has unfortunately been parked since. I started it and let it idle to warm once a week or so when I went on Vacation for 10 days. Before going on vacation I moved the car and after warming up everything seemed to be normal. Unfortunately I neglected it once I got back and haven't started it since the beginning of December. I'm selling it here soon and so went out to spruce her up tonight and upon trying to start the battery was dead so a buddy came over and jumped it.
It started right up but immediately was idling funny which I assumed was because of the cold (it's 25 degrees F tonight and has gotten in the negatives in the past few weeks due to snow storms). I shut it down and checked the fluids which were all pretty low especially the oil due to a small leak. So I topped off the all the fluids and started it again and let it idle to full warm.
I decided to take it for a drive around the block and it was still driving pretty rough, no knocking or anything but the engine was "sputtering" and the CEL was on and flashed when I gave it gas. I'm running stock boost so my gauge usually reads around 12psi but is now only going up to 3-5 psi and the vacuum is only at -15 which i think used to idle at -20. I drove it to the gas station and filled it up from a little less than a half tank but it's still running the same and there's a slight burning smell from the exhaust.
I was worried it was my turbo but it was perfectly fine a month ago. I was thinking of throwing some Seafoam or Heat.
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Okay, here's the car
AWP 1.8t mk4 GTI.
- stock DP
- Forge 007 splitter adjusted 25 clicks
- Swiss cheese stock intake with k&N high flow
- APR stage 1 93 tune.
My boost gauge is currently reading peak of about 15-16 psi. I replaces some vacuum hoses that appeared to be worn, and to no avail. I have no CEL, and no codes thrown at all. This sound like a boost leak.
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I just replaced my my k03s with another one with only 20k on it. After I did this, I noticed a loud screech sound when in WOT. The screech lasts a little bit after i left off the gas when revving in neutral. I've been doing research on here, and I've read that it could be a boost leak somewhere or even the turbo dying. The shaft play is minimal though.
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Recently got my VCDS USB cable that I can use on the newer 1.8T Jettas and I haven't found a measuring block for boost or MAP data. My Scan Gauges don't give a MAP data field either for the 1.8T engine, while it does for the TDIs.
Where do I find this data? Surely the ECU monitors boost?
Couldn't find anything while hooked up to the Buddys Passat 1.8 that we did a TB and thermostat on yesterday.
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Ok so my 2002 gti is having some boost problems... Instead of hitting boost consistently the boost is fluctuating for example hitting 12 psi then 15 psi and it just hits and bounces back to 0. what could be problem I was thinking bad downpipe, bad waste gate, or bad n75 valve.
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Bought a 1.8t 04 gli. Was boosting 15 pounds so i did a boost leak test. Found pcv up hose from valve to y pipe at valve cover was almost blown in half, so i replace all of that stuff with oem.
Boost leak test again, found where boost gauge is hooked up to, turbo outlet to n75, the hose was leaking, i fixed that.
Boost leak test yet again, n75 was not clamped down, so clamped that.
Boost leak test one last time, held 10 psi before blowing the cap out of the intake. Which is pretty dangerous, my cap is made out of a spray can cut in half. Sounds like a canon. Anyways i heard zero leaks.
So now I am boosting 18psi and holding perfectly fine. Why I am showing ZERO vacuum on my boost gauge??
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2003, Jetta 1.8t, 5 speed, 76,500 miles ... The other day I was driving and all of a sudden I had a hesitation in 3rd gear. I have relized since that this hesitation occurs in 3rd 4th and 5th gear, but not 1st or 2nd. I am going to change the spark plugs tomorrow in hope to fix this problem. The hesitation occurs whenever you get into the gas and begin to accelerate(typically around 3000RPM and up). There are no dash lights on at all and the cars is running fine besides the hesitation.
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I'm having a strange, very high-pitched, noise that seems to be coming from my turbo or (possibly) somewhere else in the engine bay. It sounds very screechy, and it may be paranoia, but I believe it also may have a slight metallic sound to it.
It all started yesterday after changing the thermostat housing for the third time in 2 days (autozone sold me a faulty, warped, housing that leaked after install). During this repair the engine never overheated (it did however leak fluid and go a little low) and the main point for replacement was a stuck thermostat. After finally getting it fixed I took it for a test drive and noticed the horrid noise after hitting a good amount of boost (no gauge installed). The noise occurs when boosting and doesn't happen when spooling in the 3k-4k range. I had no hint of the noise before this.
There doesn't seem to be any drop in performance and it still pulls hard. Hoping this to be a loose exhaust connection or boost leak. May be spooling sound escaping.
Mods:
- short ram air intake with an aem filter
- 3" turbo-back exhausted
- revo chipped
- 4 bar fpr
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